Yeah, Looking for Alaska is really good, though I wouldn't recommend it to anyone who is easily upset. (But you read the Fault In Our stars so you should be fine.) It's a bit more mature to read, but has a great plot and is well written.
I've read all books by John Green and I can say that they're all really good. If you want a sweet love story, try Let It Snow by John Green, Maureen Johnson, and Lauren Myracle. It's three romance stories all interwoven into one amazing plot!