I have a quite a few different things I like, most of which I do indeed like for there to be some sort of romance or sexual tension to be present. However, though I might like for there to be romance and sex and what not, I MUST have plot. Without plot, I might as well not bother RPing because if it's just the sex aspect.... yeah.... I get bored and VERY unhappy and feel like I'm wasting my time. It's just how I'm wired.
Anyway, as for subjects? I have a few genres I enjoy, for starters: fantasy (this can be medieval, modern/urban or even scifi fantasy), steampunk, hard scifi, cyberpunk, apocalyptic/post-apocalyptic scenarios, dystopic scenarios, horror, pirate themes to name several. But I also enjoy RPing in certain historical settings such as ancient Rome or Greece, medieval times, the Renaissance, the Victorian Age, the Regency Period, the Old West/pioneer times... along with certain fandoms--particularly Riddick, Sin City, Harry Potter, Firefly/Serenity, Tolkien, Dune, Zelda, Castlevania and various storybook settings (ie, Alice in Wonderland, Little Red Riding Hood, Snow White and the Huntsman, etc) to name several. As you can see, my tastes are quite eclectic. But, I think this is a good thing since it broadens my scope and keeps things interesting.