Regarding the "The Sims" you may want to check out a game called "Singles: Flirt Up Your Life!" or its sequel "Singles 2: Triple Trouble." http://www.singles-the-game.com/
Of course, there are also mods and expansions for those games to further expand on the experience.
For Hentai games, I'm more of a fan of games that have an additional gameplay element in them aside from reading one chapter after another separated making a series of Yes/No choices that require the right combination to reach the Happy End. A simple example would be "Maid's Story." Though the Japanese seem to have a rather perverse take on sex that may be a bit to explicit for some people.
I do enjoy Goblinboy's work very much, but, to me, both "School Dream 3" and "Meteor" both feel like they're complete the way they are, even if I'm not happy with "Meteor's" ending. He writes an incredible amount of detail for the player, with a good number of options to explore. Though I feel that if he bumped up the media aspect of his games with animations and music, that those things might somehow detract from the game.
Regarding dating sims, I do like, the 100 days to accomplish your goal by building your stats and learning more about the prospective girls. But even then there are a few terrible versions out there as well. I still think Leonizer's "LoP2" is one of the best in that regard. I did also enjoy his twist on that with his "500 series."
Finally, there are the Virtual Date games which seem to be in abundance on these boards. I'll just say that "ArianneB" is the best, and I'm waiting for someone to top her work.
There are many different times of games out there, and I honestly can't say that combining different elements is such a good idea, that's not to say "it can't be done and done well." What I do like, as evidenced from the games I listed, is more options. More places and activities to explore. Let me be curious and discover new sexy secrets!
EDIT: Hotlinked Link