I've sailed:
RCCL: (With Only DW, no kids). It was great. Food was good. Did not see a lot of kids. Price was good too. Not a single complaint
Holland America. "Old fogey's" (not for a young 51 yo)
Royal Olympic: Very European (It was a Greek Cruise). Many smokers, and people talked on their cell phones constantly, even through dinner.
Disney: Most fun vacation I've ever had, both with the kids and without. The people we met on the ship had similar likes as us (like Disney, duh) and everyone clicked. The activities were well organized, the food was great.
Only downsides of
DCL (can't call them negatives) was
(a) lack of casino. DW likes to do them on cruises.
(b) it is pricier than other lines, but it was worth every penny.
We are going on a Celebrity Cruise next time, and would love anyones comments on that.
Jim
PS, One of the group of friends we met on the ship was a couple about your age, with no kids. They had a ball, apparently. They rebooked on board with us and with EVERY ONE in our new group of new friends.