If you're hoping for the Star Princess to be smaller than the CCL ships, I think you're out of luck... Star is a monster, biggest class of the Princess fleet -- 109,000 tons / 2,600 passesngers. If you want a smaller ship take one of the "Sun" class ships - - Sun or Dawn - 77,000 tons / 1,900 passengers ...or the Regal - slightly smaller but roomier, and really nice. ...or if you want one that still slightly resembles a ship rather than a building, take the Royal, it's close to 20 years old now, but still pretty nice for its age.
Princess pretty much puts their whole fleet in Alaska during the summer, so you'll have your choice of ships. July '05 is a long way off though, so it's hard to know what they'll have sailing up there at that time. Don't necessarily rule out the "Grand" class ships (Grand, Golden, Star)... even though they're big, you still get a really nice experience on them.
I think you'll like Princess.
Good Luck !