Hi there! :)

What a great question, but first we must subdue all the nerds you angered with your post!

other luxury cruise ships of it's time

Titanic and Mauritania were ocean liners, not cruise ships. Not only is this important to save you the wrath of Titanic nerds, it's how we begin to answer your question.

You have to begin by understanding the world in which these two ships were built- that is, the peak of the second industrial revolution. Suddenly, communication and travel between the America's and Europe and never been easier, faster, or more rapidly expanding. A new, global economy was starting to take shake and it was fueled by shipping lines who traveled all over the world but were most often found on the run from England to North America- and the run which these two ships were built for.

Ocean Liners aren't cruise ships. Ocean Liners were responsible for mail, supplies, business, travel, and immigration and while yes, the rival lines built amenities to make that trip more enjoyable- the trip itself was necessary for the world economy to function. Nothing much will happen if Disney cruises skip a Barbados run. There would be economic and social consequences if ocean liners missed their schedules.

And in response to that growing global economy, shipping boomed at a rate never seen before. In 1902, the biggest ship in the world was RMS Celtic at 20,000 tons. Ten years later, Titanic would sail- doubling her gross tonnage at over 46,000 tons. In the decade between them, each ship that took "the largest" prize was exponentially bigger than the one before it- and they were coming out every year, and then a few times every year. Titanic herself was only going to last a year as the largest, the German Imperator was about to be launched as she sailed.

And in between there, in the autumn of 1907 sailed the Mauritania- at the time not only the largest object ever built, but the fastest ship on the sea. She, and her sister Lusitania were impeccably designed- multi story, domed dining rooms decorated in a French Renaissance style, outdoor cafes, and even elevators. This was all complimented by an interior designed by London designers and architects working on manors and grounds around Britain. Suddenly, the busy North Atlantic shipping lanes were dominated by two new liners who could not only get you across the ocean in less than a week- they could do it in extravagant luxury.

For a long time, the official story was that White Star Line- about to witness the sailing of these two new speedy, luxurious, ocean liners- sat down in the summer of 1907 to top the Cunarders with their own ships- BIGGER ones!

Except that's not quite true. White Star had given the go ahead for the Olympic Class Liners that April, and the docks and gantries needed to build them were ready in the preceding years before 1907. Mauritania and Lusitania, and everything they were projected to be, would have been public knowledge by 1902. White Star wouldn't have waited 5 years to think of how to compete. The Olympic Class liners were being planned well before 1907.

So while Mauritania enjoyed 3-4 years as the worlds largest ship (and an astonishing twenty years as the worlds fastest), White Star Line prepared the first of two behemoths- Olympic and Titanic.

Speed was never going to be a factor for White Star Line- they didn't have the backing to provide their new class with the four steam turbines Cunard had. Instead, they set them up with good old reciprocating engines and a turbine for the central propellers and decided that luxury would be the answer to speed.

And it was- swimming pools, Turkish baths, a squash court, separate restaurants with their own French and Italian staff, staterooms with private bathrooms and private decks, a French cafe, a gym- all things not found on Mauritania or Lusitania. White Star also use the Cunarders strengths against them. The high speeds of Mary and Lucy caused the ships to vibrate violently, and their sharp design made them prone to pitching and corkscrewing. The Olympic Class Liners may have been a tad slower, but vibrations were minimal and they were fatter and steadier- Olympic would be known for plodding through storms and weather that ripped her paint off but couldn't stop her moving steadily.

On top of that, while the Cunarders were fast- they weren't fast enough guarantee a dependable two week turn around on the fast moving North Atlantic shipping track. In response, for guaranteed steady service, White Star began construction of a third superliner, the largest, Britannic- setting Cunard scrambling to top them with their own addition to the duo- Aquitania.

Still, though, for all the talk of "the most luxurious ships in the world", there were parts of Titanic and Olympic that weren't as grand as Mauritania and Lusitania. The White Star Liners dining room featured long ceiling, single floor, with thick carpet, tile, and dark paneling. Comfortable- but much less opulent that the multi-story Mauritania lit by a brilliant dome. However, they did feature actual leather chairs - not the ship chairs bolted to the floor on Lucy and Mary, despite being slightly warm tempered due to limited ventilation. Also, even the Kaiser Wilhelm De Grosse, so old at nearly 20 had a dome in her one story dining room.

Most strange though, was the design of the swimming pool. Although White Star had started putting swimming pools on their ships a few years before, it was still a great novelty so it's strange that they put absolutely no effort into its design- merely painting the walls white and putting the pool in a room that was just the outline of Titanic's hull. This was especially odd considering the German Imperator under construction included a gorgeous, two story swimming area- so the technology was new, but available. White Star simply chose to keep theirs simple.

And still- not all passengers were happy. Second class passenger Imanita Shelley complained-

instead of being assigned to the accommodation purchased, were taken to a small cabin many decks down in the ship, which was so small that it could only be called a cell. It was impossible to open a regulation steamer trunk in said cabin. It was impossible for a third person to enter said cabin unless both occupants first of all crawled into their bunks.

After eleven attempts to speak to Purser H. McElroy, Shelley threatened-

that she had paid for the best second-class accommodation on the ship and had the receipts to prove it; that she was very ill and, owing to that freezing cold of the cabin, was in great danger; that if he, the purser, refused to act she, Mrs. Shelley, would appeal to the captain; that if neither would act she realized she would have to wait until reaching America for redress, but most assuredly would claim damages if she lived to reach her native land.

After being moved, she continued to complain- referencing Mauritania-

That this cabin, though large and roomy, was not furnished in the comfortable manner as the same accommodation procured on the Cunard and other lines; that it looked in a half-finished condition; that this room was just as cold as the cell from which we had just been removed, and on asking the steward to have the heat turned on, he answered that it was impossible, as the heating system for the second-class cabins refused to work. That of all the second-class cabins, only three - the three first cabins to be reached by the heat - had any heat at all, and that the heat was so intense there that the occupants had complained to the purser, who had ordered the heat shut off entirely; consequently the rooms were like ice houses all of the voyage, and Mrs. L. D. Parrish, when not waiting on her sick daughter, was obliged to go to bed to keep warm.

And on and on Shelley complained- the stewards were lazy, and late, didn't bring her her meals, when they did they were cold. The doctor forced her to stay in her cabin, the bathrooms weren't nice enough, the lifeboats took too long to lower, "an Italian" jumped in the boat and hurt her mother, there was no food in the lifeboat...

So irate was Mrs. Shelley that upon rescue by Carpathia, the first thing she did was head to the third class survivors and ask them if they had heat in their staterooms.

And then, she became hysterical- Captain Smith was playing cards, she said, ignored the iceberg and told everyone there was nothing to worry about, she wasn't even told about the accident by her regular steward, she was so sick it took her too long to get to a lifeboat and- perhaps most egregiously- she had paid £1 each for several wireless messages that had not been delivered!

Poor Mrs. Shelley.

And what got so many people sold on the Titanic

A perfect storm of circumstances. Titanic became a legend because she sank when she did and how she did. In reality, had she have lived, she would have enjoyed a year as the world's biggest ship before being overtaken not only by the German liners but her own sister. She would have been the forgotten middle sister to her more famous older one and biggest younger one. And they all would have been one more ship in the never-ending boom that was dominating the pre-air travel world.

But, Titanic became...well... Titanic and with that so did she start to mythologize. Was Titanic luxurious? Incredibly- ridiculously. But she did have her critics and she wasn't quite done when she sailed. Was she the most technologically advanced? No. She had some amazing modern amenities and safety equipment but Mauritania was running on turbines far more advanced than Titanic. Was she the fastest? Never stood a chance to be.

In context, the only surviving sister- Olympic- ended her career known as "Old Reliable"- a beautiful, old, stately, steady, plodding, well made ship. Titanic just happened to become frozen in time at the exact moment she was the biggest, best, most famous and most luxurious ship ever made.