The first cruise I ever went on was last year on the Grand Princess. I loved the trip so much I decided to go again this year on the Caribbean Princess. The Grand and the Caribbean are the same size, but the Grand holds 2,700 passengers and the Caribbean holds 3,100 passengers.
On the Caribbean Princess I felt the boat was too small for the amount of passenger they had aboard. On the Grand I had no problem going swimming on the Caribbean I had major problems. I could not get near the pool. Once I did there was no room to go swimming. The whirlpools where way over crowded and one did not work for the length of our cruise.
On the Grand if you wanted to see a show no problem, always room. On the Caribbean if you did not get there at least half an hour before show time forget about getting a seat for two, and same with the show lounges in the back of the ship, very hard to find seating. The shows where very nice.