What cruise line should I choose? Are any not gay-friendly?

I'm looking to book a cruise in August--we're a gay couple, both 24 years old, live in Chelsea, NYC, young professional types/in grad school. We want a cruise line where we won't be surrounded by either baby strollers or a geriatric crowd. We like to drink and have a good time, but we don't want to be in a crowd that feels like a frat party either. I've taken a few cruises before, all on Royal Caribbean, with my family. I've had great experiences, but I also get the impression that Royal Caribbean is very family-oriented--that's great, it just may not be for us. I would really appreciate any suggestions that anyone has. Thanks!