Someone in my online class asked my why Charles II was my favorite English monarch and this is what I replied:
I suppose part of my liking for Charles II is based on childish romanticism. My first knowledge of him came from Forever Amber, which was a fictionalized and quite idealistic view of him. But even knowing what I know now about his backstairs dealings with France and his tendency toward absolutism, I think of him more as a pragmatist than a tyrant (not that the word tyrant applies in the least) and the English parliament had a much stronger role in his reign than in those of previous monarchs so he resorted to secret deals to get what he wanted on more than one occasion.
Charles was also deeply interested in science and learning and promoted it throughout his reign.
His religious tolerance is of interest but to be honest I think it goes back to his pragmatism, not his morality. His own religion, if he had it, ran mostly toward Catholicism but even in that, not too strongly. He converted to Catholicism on his deathbed but I think he would have done it a lot earlier if he truly believed religion to be an integral part of life. It may have ultimately been a means of salvation, but certainly not something to adhere to day-to-day so he waited until the last minute to convert. He kind of had a live and let live attitude, though critics would probably call him wishy-washy.
Finally, the restoration was a unique period in English history and I find the contrast between puritanism and the "merry" time that followed appealing. He was looked upon as a savior (from puritanism at least) of sorts by the English populace, and though he believed in the "Divine Right of Kings" and his rightful place on the throne, in the end, he was just a man who wanted to enjoy life and didn't mind so much if his subjects did too.