Mommy and Daddy need some alone time? Many cruise line kids clubs don't accept babies and toddlers — and some won't take small children if they're still in diapers. Sure, some of these ships have in-cabin babysitting or special hours in the playroom dedicated to parent-supervised play for toddlers, but if you want substantial grown-up alone time you're going to want to pick a ship with a proper nursery, where your little one can play with toys, and maybe take a nap.

Great Choices: On Disney Cruise Line ships, babies and toddlers can romp around a colorful nursery decked out with an "It's a Small World" or "The Little Mermaid" theme. On Royal Caribbean ships, the Royal Babies & Tots program is designed specifically for children from six months to three years old, as is the Guppies Nursery on Norwegian Cruise Line's Norwegian Escape.

Make no mistake: Kids want to find other kids their age on board, to have people to play with when they're not with their family. They also want a space to play in that caters to their age group, and experienced counselors to keep things fun. For rainy days — and for those kids who just can't unplug — video and computer games are always welcome, too.

Great Choices: Disney, not surprisingly, has an impressive roster of activities in huge, themed, age-appropriate playrooms — with Disney, Marvel, and "Star Wars" characters, depending on the ship. Just how good are these programs? You may have a hard time getting your little ones to leave. Royal Caribbean has elaborate playrooms with DreamWorks characters on board, and Carnival has a particularly good kids program with a Dr. Seuss tie-in. Both Disney and Royal Caribbean offer programs that allow children to start the evening at dinner with you, and then get picked up by kids clubs counselors to play while you linger over your meal and check out the entertainment. Norwegian Cruise Line also has a good program, even though they have phased out their Nickelodeon partnership. 

They don't really want to hang out with those intimidating teenagers, but they don't want to be stuck with the little kids, either. And while some tweens are perfectly happy with some sunshine and a good book, most want activities to make this feel like their vacation, too. 

Great Choices: Royal Caribbean offers specific activities geared for ages 12-14. On the newer Carnival ships, the Circle C club is reserved just for tweens. And on Disney Dream and Disney Fantasy, ages 11 to 14 get prime real estate in the Edge activity center right near the must-do AquaDuck "water coaster," giving them a major advantage when they want to get in that line. 

Everyone knows teens don't want to get stuck vacationing with their parents. But yours will forget they ever rolled their eyes when they see the cool teen lounge, the game terminals, and plenty of cruisers their own age.

Great Choices: Disney Cruise Line serves teens so well they even have a teen-only beach area at the cruise line's private island in the Bahamas, Castaway Cay. On Disney Dream and Disney Fantasy, the teen clubs (for ages 14-17) are like cushy coffee bars, with large TVs, a dance floor, and a DJ booth — plus an outdoor sunning area with water features. You might also consider a new ship by Norwegian, Carnival, or Royal Caribbean for fun attractions such as racing waterslides, ropes courses, bowling alleys, and even bumper cars and roller skating parties.

You want to relax in the sun by day and party by night. Having access to a great gym, a pool with a DJ, and a good selection of bars and clubs — that actually stay open after midnight — are also requirements in these post-college years, now that you (finally!) have your own money to spend on vacation.

Great Choices: Go with an affordable three- or four-day cruise to the Bahamas or Mexico on a line like Carnival — the shorter and less expensive the sailing, the more likely you are to find young singles and couples also in their 20s. Remember: People tend to sleep in late on sea days on these ships, recovering from the night before, so early risers may have the pool deck — and the gym, and the dining room — all to themselves before noon. 

The hottest attractions at sea tend to draw the most 30-somethings, whether they are sailing in pairs or with children in tow. 

Great Choices: For the most state-of-the-art attractions, look to new, large ships — such as Norwegian Escape, Royal Caribbean's Harmony of the Seas, and Carnival Vista — where like-minded cruisers are drawn to great restaurant options and Broadway-caliber entertainment. For those who drink, elegant wine bars, gastropubs with well-curated beer selections, and lounges serving hand-crafted cocktails are also appealing. Picking a cool itinerary — such as a one-week Mediterranean sailing that's packed with exciting cities — will also lower the age demographic on board. 

It's not that you don't want to party, but you like things a little ... classier. You want a nice spa, spaces with style, and a quiet plot of pool deck where you can lounge in the sun without a crowd — even if you have kids enjoying themselves on some other part of the ship.

Great Choices: If it’s in your budget, consider a newer ship from Celebrity, Princess, or Oceania, where the design is more sophisticated. Regal Princess and Royal Princess have elegant adults-only pools and private cabana areas, while Celebrity's Solstice-class ships have gorgeous lounge-like seating — with egg chairs and hammocks — across the vessels. Oceania's Marina and Riviera have impressive decor, great Asian and French restaurants, a very cool hands-on cooking school, and unforgettable art collections, too. 

You want to treat yourself, and maybe even have more of a "private yacht" experience. Because, you know, you've earned it. 

Great Choices: Viking Ocean Cruises and Windstar offer a sense of class. (Viking's amazing Scandinavian-style spas — with their co-ed steam rooms and hot tubs — are reason enough to book.) A Baltic itinerary may appeal to you if you've already seen Alaska, the Caribbean, and the Mediterranean, as could some more off-the-beaten-path itineraries in Asia. If you're looking to get out into Zodiacs and closer to nature, you'll find adventure with Lindblad Expeditions-National Geographic.

You plan to spend the kids' inheritance seeing the world, doing all those things you've been putting off. On your to-do list every day: Looking for last-minute deals on amazing cruises, and plotting the last few items on your bucket list. 

Great Choices: Consider Azamara or Cunard, where the passengers love great lectures, card games, and cocktails with hors d'oeuvres before dinner. Regent, Seabourn, and Silversea offer luxury and a decadent, genteel atmosphere that may remind you of your club back home. Your time is your own once you retire, so do look at all those long sailings you never had enough vacation time for before now.