I went on a cruise many years ago and it was awesome... and no, absolutely not boring! Besides so many things to do onboard, the ports of call allow you to see places you might not otherwise, and there are all kinds of activities in the ports to choose from (or do your own thing...). My favorite day included driving around Puerto Vallarta with a group of new friends from the cruise in a rented van with a driver, shopping in the crazy open markets, drinking too much tequila, a great lunch by the ocean, and parasailing! Then back to the ship for yet another great meal (dinner), and then choose from a multitude of bars, casinos, clubs, or quiet decks on board.
We're heading off to Napa in early October, hooray!!!! Made the arrangements yesterday!