It's no easy feat appealing to grandparents and parents, uncles and aunts, and kids of all ages while miles from land. These ships succeed

Carnival Splendor
Line: Carnival Cruise Line
Passengers: 3,006
Itineraries: Europe
Great kids' programs, an enormous spa, four pools, 22 different bars and lounges—there's plenty to appeal to all ages aboard the just- debuted Splendor. And since a weeklong Caribbean cruise starts at $649, no one will quibble with your choice; this is one of the best values at sea. One caveat: Carnival requires that you fill each cabin to capacity, so if one person drops out, her cabinmates will have to switch rooms. Camp Carnival caters to ages 2 through 11, Circle C to 12 through 14, and Club O2 to 15 through 17. Mom and her sisters might enjoy a spa treatment while Grandma walks the promenade. Everyone can go their separate ways during the day and meet back at the main dining room or reservations-only Supper Club for dinner (888-227-6482; carnival.com; 12-day European trip from $1,400).

Crown Princess
Line: Princess Cruises
Passengers: 3,070
Itineraries: Caribbean, Europe, North America If your family is uniting to celebrate a wedding, the Crown Princess's captain can perform the ceremony in the ship's chapel. While the happy couple honeymoons, kids can color T-shirts, teenagers rehearse for the talent show, and parents take advantage of the golf simulators, wine tastings, and ScholarShip at Sea program. The Sanctuary, an adults-only relaxation area, has waiter service and cabanas for massages. This isn't the right choice for the smallest tykes, since the only connecting cabins open through the balconies.There's more flexibility in the dining, with both fixed seatings and anytime restaurants (800-774-6237; princess.com; ten-day Scandinavia and Russia trip from $1,600).

Liberty of the Seas
Line: Royal Caribbean
Passengers: 3,634
Itineraries: Caribbean
Can't agree on what type of cabins to book? This ship has tons of connecting rooms, in many cases from different price categories—so your teens can stay in an inside cabin while you unwind on your private balcony. Tweens flock to the water park and mini golf course, while the younger set enjoy the Adventure Ocean program's science classes and scavenger hunts. At the solarium adults-only pool area, two cantilevered whirlpools—suspended 112 feet above the ocean—are popular places for reading a book. Though kids are welcome at all restaurants, Chops Grill and Portofino's see few of them. The main dining room is, however, another matter; here everyone congregates for meals en famille (866-562-7625; royalcaribbean.com; seven-night Eastern Caribbean trip from $749).

Noordam
Line: Holland America
Passengers: 1,918
Itineraries: Caribbean, Mediterranean, Transatlantic
If the teens rule your group, they'll love the Noordam's Loft and Oasis deck areas, exclusively for their use. The former, resembling an artist's New York loft, has TV, Internet, video games, and karaoke. The latter is a sundeck with a waterfall, a snack machine, and dancing. Grandparents will appreciate that this ship is somewhat smaller than the others listed here, so they won't have to walk the length of several football fields just to get to dinner. The "sandwich generation" can spend their days in the demonstration kitchen, library, spa, salon, or the Crow's Nest at the prow, a lounge by day and club by night. There are two pools, one adults-only (877- 932-4259; hollandamerica.com; ten-day Mediterranean Enchantment trip from $1,340).