Which cruise line should I go with?

Since your 21 and not 25, you can't go with Carnival. But that's Ok because I prefer Princess cruises. They have a huge variety of places to go. If you insist on a cruise during the Summer, then how about Alaska. I'm going back to Alaska this Summer with Princess for the second time. With Princess, tipping is now $11 a day per person. They automatically take this out and charge it to your credit card. If you buy alcohol, then they tip that as a extra and automatically take that out too. If you want to add or subtract from your tip, you can do so by going to the pursers desk at the end of the cruise.