My wife and I are both in our 30's and we take a "honeymoon" cruise with Oceania every year. We've found ourselves one of the younger couples on board, but we've also found a handful of couples our own age to hang out with. We like the slower pace of Oceania - we've sailed on other lines and grew tired of the incessant pace of activities (bingo, conga lines, disco nights, sports tournaments) and constant sales pitches (art "auctions," port "presentations," shore excursions, and daily drink specials).
The most excitement you'll find aboard are the daily bridge game (for those who don't care to go ashore), a ping pong table for those who can find a willing partner, and the afternoon trivia contest. There's also a small golf driving tent on the upper deck and a shuffleboard mat, but I've never seen them used. There's a disco in the evenings, but the music usually shuts off around midnight as the passengers head off to their staterooms to prepare for the next morning's tours. We've closed down the bar more times there than I'd care to remember!
We prefer Oceania because Oceania "lets you be" and allows you to set your own pace, free of any pressure from the company. You can let them book your air, or you can book your own. You can let them make your transfers for you, or you can make your own. You can take their shore excursions, or you can arrange your own. And if you didn't have the time to arrange for private shore excursions ahead of time (which I highly recommend), the destination services desk can arrange a private guide and/or driver for you. If you're an early riser, you can take a morning half-day trip, or if not, you can sleep in and take an afternoon excursion. Or you can slap on your backpacks and strike out on your own, as we frequently do (we like to think of the Insignia our upscale "hostel"). Oceania truly lives up to their motto "Your World, Your Way."
Richard & Judy
P.S. If your preferred cabin category isn't immediately available, have your travel agent put you on the waitlist ASAP - we've found that people are cancelling up to the last minute, and we've always got the cabins we wanted. If Oceania knows you're a guaranteed PH Suite customer, they may opt to bump an Oceania Club member (like us!) from a PH up to an otherwise vacant Vista Suite, like the airlines do.