You bet! I've sailed the Sea Princess twice, the Sun Princess twice, the NCL Sky twice, and will probably sail on the Epic again when I book my next NCL cruise. I'd sail the Sea Princess 100 times and never get tired of her, she's just my favorite. LisaP is so right, there are always new discoveries on board. Plus, they're always upgrading the ships, so they add or change things all the time.
It's also exciting to sail on a new ship, too.
So, my suggestion is, find the itinerary/price you want and the ship next. You know you're going to have a marvelous time:)