My husband & I wanted to go on a cruise without kids. We chose the Disney Dream - and left our kids at home. We heard that Disney was world class - and they did not disappoint! We were never lacking activities to do....martini/champagne/wine tastings, multiple lounges & bars, adult only pool & hot tubs, bingo, etc. As for evening entertainment, they offered several movies/comedy shows/game shows that were geared towards our age group. The adults' only pool, hot tub and Serenity Bay beach (Castaway Cay) were never crowded. We snorkeled almost every day at the ports. Castaway's snorkel area was large and once we left the shallow area, we were mostly alone. I would recommend bringing your own snorkel gear if that's something you'd like. We paid over $100 for three days worth of gear! And we were also able to snorkel on the adult beach which is amazingly huge. The underwear life was amazing!
Disney had wonderful service and was very clean. Sanitizing wipes were handed out at every entrance to restaurants and embarking points. At the ports, the Disney Dream boat was the prettiest boat. It made be beam with pride that we chose the right ship. Onboard, the noise was never an issue, despite being the first door next to the elevator. Food was great, but I would not recommend paying extra for Remy or Palo. The food was good, but for the extra money, I didn't feel it was much better. We did have to sit with other couples in our dining rotation, but our friends (who booked through an agent) were able to get their own private table. Drinks onboard were expensive, although the drink tastings were worth it! We bought a a bottle of rum at Nassau for $14 (which is the same cost as one onboard drink) and were able to drink unlimited rum & cokes.
Overall, I recommend Disney for adults! We are already planning on our next trip, although we may take the kids next time, to share it with them.