We just got back from the Wonder cruise on Sunday. We used American and thought they were great, except that we were told they would have booster seats for the kids, and they had one booster and one regular car seat (my kids are 6 and 8- car seat was not appropriate). Since my son is close to being out of the booster, it wasn't a huge deal, but I was disappointed that they said they had 2 boosters guaranteed and they didn't. We used them for 3 trips- airport to hotel (booster and car seat-mentioned to driver that the seats were wrong), hotel to port (one booster- complained to driver and called company- driver said by law, kids didn't need a booster in CA for their ages? not sure on that- called company said they would have them for our return- also explained we needed booster, not car seat) and port to LAX (booster and car seat- ended up letting ds use regular seat belt and dd use booster and complained to driver).
In a nutshell, as long as you don't need 2 booster seats- or car seats at all- I would definately recommend American! Everything else about them was great- always on time or early, clean cars, nice drivers!