I wouldn't choose Liberty as there's not a Playmakers, Izumi or poolside eats like El Loco Fresh or Fish & Ships. But as new cruisers, you wouldn't miss those things! 7 days is the bare minimum. I prefer 9 or 10 as you need days to do all the things and then days to do nothing. I also like the Freestyle machines because of all the Vitamin Water flavors and Freedom doesn't have any. If you want to knock first-time cruisers socks off, I would choose Wonder! I'd also look into VV. A friend of mine recently went and had an amazing time. She's in the 50+ crowd. She loved that there weren't any kids on the ship. She felt it made a big difference. Whichever your group decides, I hope you have an amazing time!