A picture of Philip II's daily life was elaborated in Geoffrey Parker's "The Grand Strategy of Philip II", ISBN-10: 0300082738, 2000. Philip II's reign lasted 1556-1598, depending on which kingdom or duchy or county you speak of.

As a deeply religious man he went to Mass each day, although he didn't always take communion. As king of a humongous, global empire, he held many audiences and undertook large volumes of correspondences, in which he preferred to write his reply on the margins of the original letter, often asking his ministers or secretaries to fill in the details. Indeed, Spain's postal service was so reliable that even the embassy of France used its service to correspond between Paris and Madrid.

A lot of his time seems to have been spent reading and re-reading and re-deliberating decisions, either alone or with his advisors. Pope Pius V lamented, "Your majesty spends so long considering your undertakings that when the moment to perform them comes the occasion has passed and the money has been spent."

In the end, given how poorly the system was set up to govern a global empire, it was said that, "His majesty's brain must be the largest in the world."

Besides his governmental duties, Philip II seems to have been very conscious of his two personifications: as a (family) man and as king. His new seat of government in Madrid, the El Escorial, had two main levels. On the upper level he lives with his family, and downstairs was where the government officials worked. He would tell his secretaries to not bother him at certain times of the day because he wanted to spend time with his family. And like many royals of the time, he occasionally took vacations.

Edit: To quote J. H. Elliott's "Imperial Spain: 1476 - 1716", ISBN-10: 0141007036, Penguin, 2002: even if Philip II's reign was part of Spain's Golden Age, not all was well in Philip II's reign, in particular in his family life. The Habsburgs' tendency to inter-marry is well-known, the outcome was terrible as many of their children didn't survive childhood.

Through the life of Philip II there filed an endless succession of funeral corteges, tragic reminders of the mortality of princes; and the King, to conceal his sorrows, taught himself to maintain an icy self-control, and devoted himself with redoubled energy to his solitary labours.

He had to endure the deaths, or still births, of eight of his eleven children; only three survived to adulthood.

The Middle Ages is a pretty huge period that spanned centuries, so you might want to refine your question. The daily life of a monarch in the 8th century was incomparably different from that of a 16th century one.