Although I was happy enough to read the Rainbow Boys books when I was younger, it was mostly just because it was novel to read a book that featured gay characters. Now, compared to other stuff I've read, I have absolutely nothing good to say about the books. "Let's see how many trite gay cliches we can fit into a series of three books!"
If you're going to read LGBT-themed YA books, I would look into David Levithan before picking up Rainbow Boys.
Will Grayson, Will Grayson (cowritten with John Green) is wonderful, as are Wide Awake and The Realm of Possibility. Boy Meets Boy is cute, too, but I don't like it as much as the others, for some of the same reasons I didn't enjoy Alex Sanchez's books. (Although Boy Meets Boy was soooo much better.)
Mercedes Lackey does an interesting fantasy trilogy with a gay protagonist, The Last Herald-Mage trilogy. It's definitely not Tolkien (or Jordan, or Martin, or Pratchett....) but it's not bad.
If you like horror, check out Poppy Z. Brite. My favourite book is Lost Souls, although I think Drawing Blood was technically better written. Her characters (especially in her newer works) are awesome. Love her love her love her.
Suicide Notes by Michael Thomas Ford is another favourite, as is Pretty Things by Sara Manning.
Anne Rice's son Christopher Rice wrote a sort of crime thriller that was decent, Light Before Day.
Finally, I'm going to second Mito's recommendation for The Picture of Dorian Gray. It's not technically a "gay" book, but it's a good read nonetheless. If you get a chance to see The Importance of Being Earnest (also by Oscar Wilde), do it. It's hysterical.