Last month we sailed on the Diamond Princess to Mexico and it was wonderful. The food on Princess ships is very good and I would recommend it to a younger couple. We also enjoy days at sea more than port days, and you don't have to get off the ship on days in port if you don't want to. Royal Caribbean is a comparable cruise line - comparable in price, cabin size and layout, food etc. I did like RC entertainment a little better - they had "name" entertainment usually. But Princess entertainment is good. You won't go wrong with either Princess or RC. If you go when school is in session, there won't be many kids. We are planning our next cruise now and trying to decide between Princess or RC (or Celebrity) - but whatever we end up choosing, will be wonderful without a doubt! Good luck making your decision!
Marcy