I prefer rci over princess for teens -- voyager class ships are starting to keep their pools open later . Your kids are going to have a great time no matter which ship/line you choose.
I wouldnt look at facilities that much -- some of the newer ships have great facilities for kids -- ie. teen centers -- that often are empty -- any line is going to have lots of kids over spring break. My kids prefer rci over celebrity -- not sure why -- they also like norwegian, which i see u didnt mention.
All cruise lines have an age policy now -- pretty hard for someone under 21 to book a cruise without an adult -- so i think the problem with college age and spring breakers is going to be handledd well by the cruise line.
I would prefer booking 2 rooms vs. a suite if the price were right -- 4 per cabin gets crowded if you have even one teenage girl. Usually you can get a cabin for not much more than the 3rd and 4th rate . I am not sure, there arent too many lines that offer cabins for 5 --- youre kids arent so young that I think you need to stuff everyone in one cabin , and everyone will have a much better time .
I have cruised with my 5 kids several times -- and frankly i'd rather take an inside than have to share with them again
-- Couple times I did balcony for myself and inside for kids ( was nice to have one room like this )
I always book my air separately -- and sometimes pick the cruise I take based on what might be the best airfare -- watch the prices, the flight times that look good pre and post cruise sell out fast.