Why not take your baby on a cruise? If you like traveling with your baby and you like cruises...you'll have fun! We traveled with our kids all over the place from the time they were six weeks old. A cruise would be no different....you'll enjoy the meals, time in the splash zone with your dd, shows, etc. You can use the nursery if you want to..... and with lots of families on board, you won't have the only baby.
Hot Tub? Lots of work, lots of $$$ to keep up, and everyone I know who as one doesn't even use it (except those with teenagers....). So buy one when your kids/family are older...