I've done some study on 14th century Crete; I can't speak too much to earlier centuries or other colonies, but I can offer what I know of Crete though it's not my primary specialty, so anyone who knows more should feel free to correct me. A few things that are (to my knowledge) unique to Venetian colonies: first, unlike many later colonies, these cities were held primarily as ports/waypoints for trades with the rest of the Mediterranean, rather than as regions that provided raw material goods.

There was a sharp class difference between resident Venetians and Greeks, who were often treated as lower class and limited in their abilities to hold government offices. There's some debate over the degree of intermarriage between Greeks and Latins but as I understand it, it was (unsurprisingly) more common among lower classes but relatively rare between wealthy elites. Likewise, cultural distinctions between Latins and Greeks remained distinct among the elite but less so among lower classes.

A fairly important element of Venetian Crete is the presence of slavery; owners conventionally (though not always) emancipated their slaves upon the owner's death. Slaves were often members of a household (rather than, by comparison, kept separate/lived in a separate building from the main household), and because the colonies was primarily a port there did not exist the "plantation" style of slavery because farming was not profitable. Most households that owned slaves, iirc, only owned a few slaves. Worth noting is that beginning in the 14th century, the children of a female slave and a free man would inherit their father's free status. Slave women were, as in other eras, very frequently sexually exploited.

My knowledge of Cretan government is far weaker, so I won't speak as much to it, only to say that in general, Venetians in Crete were subject to Venetian laws and could petition to have court hearings in Venice, at least in terms of dowries/last testaments (which are what I studied).

For more reading, I recommend articles by Sally McKee, and her book Common Dominion which are where I derive most of my knowledge (along with having read the collection of wills she edited and published). Hope this helps and, as before, if others know more/I've been in error somewhere, please let me know!

First, I would warn you from making a blanket statement about the monarchies of Europe.

That said, this is a good question. Loimographia is right about Crete, which should be seen as the jewel of the eastern Mediterranean in terms of island colonies. As Loimographia points out, the most important Legacy of this colonization is the creation of a second class citizen based on some sort of ethnic/racial background. The Venetian nobility/landed merchants ran sugar plantations that are the antecedent of the sugar plantations in the Caribbean.

While Crete produced a tremendous amount of wealth for Venice and her citizens, it became particularly important after the fall of the Kingdom of Jerusalem when all European powers lost colonial holdings in the Levant. The best historian in English (and sometimes writes in French and Italian) to write about the Venetian colonies is David Jacoby. I would recommend his Variorum Reprints on the subject: http://www.worldcat.org/title/trade-commodities-and-shipping-in-the-medieval-mediterranean/oclc/806984443 and http://www.worldcat.org/title/byzantium-latin-romania-and-the-mediterranean/oclc/860613002.

Unfortunately for your, Jacoby doesn't really focus on daily life in the colonies, but rather the legal structures that facilitated the partitioning of these cities. One can say, however, that by the 12th and 13th centuries colonists living in the levant began to feel the commercial rivalries that emerged during this period. The outbreak of the War of St. Sabas is probably the best example of this. In 1256, a violent struggle broke out between Genoese and Venetian colonists in Acre over control of the Monastery of St. Sabas. Although a number of compromises were suggested, the two sides broke out in a war that would set off a series of struggles between Venice and Genoa that would not end until 1381. The potential violence of the partitioned Levantine cities is further illustrated by the War of St. Sabas with various religious orders taking sides in the struggle.

I'm not as certain about the Venetian government in these colonies. The Genoese and Genoese interests were represented by their archbishop (see the Jacoby books or Epstein's history of Genoa for an account of this). The Venetian colony at Constantinople that was established in 1204 elected a podesta like any other commune. A colonial podestas in Genoa's Black Sea colonies is evident in Pegolotti's commercial manual in the entry for Caffa where the author describes how tariffs were distributed (http://www.medievalacademy.org/resource/resmgr/maa_books_online/evans_0024.htm#hd_ma0024_head_023). Angeliki Laiou also discusses this for a few pages in Constantinople and the Latins, The Policy of Andronichus II.

These colonial governments, at least the Genoese ones, operated as miniature versions of their home government. Like the administration in Liguria, the government of Caffa kept records of all commercial interaction in duplicate. The archives were removed to Genoa when the colony eventually fell. We have further evidence of Caffa and its "Latin" nature from Ibn Battuta who visited the city in the mid fourteenth century. The Maghrebi traveller describes church bells and the presence of a Genoese government that controlled the city.

Colonies, or rather settlements in Arab cities were quite different. While colonists tended to move around their holdings, in cities such as Alexandria that were ruled by Muslim governments, merchants stayed in fonduqs or merchant inns. These would have been owned and operated by men from their city and they would have a place to store their goods, a bakery producing their own food, and a bath house. See Housing the Stranger in the Mediterranean World by Olivian Remie Constable for more information about these institutions.

Resident merchants in Arab/Muslim cities lived at the peril of politics. A pair of letters between a Pisan merchant and his contact in Tunis found in Medieval Trade in the Mediterranean World, Illustrative Documents edited by Lopez and Raymond brings to light a time when Pisan piracy against Genoese and Tunisian ships caused the Tunisian government to expel all Pisans from its cities an confiscate their goods.

Regarding the economic productivity of the island colonies, they varied. Of course some of these colonies such as Negroponte served as waypoints. The information provided about this port in the 14th century Pratica della Mercatura suggests that this port, at least, mainly bought and sold goods whose provenance was further east. Some colonies in the Aegean, however, were excellent sources of rock alum, a resource that Genoese adventurers such as Benedetto Zaccaria exploited to make fortunes. Robert Lopez wrote a biography in Italian about Zaccaria years ago.

The Genoese, colonies in the western Mediterranean, like Corsica and Sardinia were all productive colonies. The published notarial chartularies from these colonies show extensive evidence of the archiepiscopal control over the export of local grain harvests to other communes such as Florence. Cyprus, likewise was an important producer of agricultural commodities, and the Genoese and Venetians fought over the island's productivity.

The last thing to note is that Venetian colonists did not always possess full Venetian citizenship, or that status was denied. Madden points out in Venice, A New History that after the fall of the Kingdom of Jerusalem, a number of foreign born "Venetians" made their way to Venice and tried to claim citizenship rights. It took some time for the Venetian government to settle this issue.

Sorry if this is more about Genoa, but despite my username, I know a lot more about the Ligurian city's history than her rival on the Adriatic. I'm also sorry if this is a bit scattershot. There's a lot to the colonialism of the Italian merchant republics. If you have any specific questions not covered here, I would be happy to take the time to answer them.