No doubt, the first place to visit in Florida is Walt Disney World. It's still king of the hill: or rather, of the very, very flat land. Spread over an area the size of Boston are: 4 theme parks (Magic Kingdom, best place with little kids; EPCOT; Disney MGM-Studios; and Animal Kingdom); two water-parks; 14 themed resorts that are fun in themselves; and more. Make sure you have a game plan, before you enter the World!
For your better understanding the theme parks are the Magic Kingdom -most like the California Disneyland, with signature attractions such as The Haunted Mansion, the three mountains (Space, Splash, and Big Thunder), etc. Classic Disney, with popular parades and fireworks. EPCOT - a sort of permanent world's fair, with international pavilions, and hands-on exhibits at Future World. Some call it educational; but Epcot also has plain all fun like the "Honey I Shrunk the Kids" and Test Track rides, excellent night-time parade and fireworks show. Disney/MGM Studios - tour the working studios, or try The Great Movie Ride, Muppet Vision 4D, the Star Tours simulator ride, and the Twilight Zone Tower of Terror drop ride, plus many live shows. Playing "Who Wants to be a Millionaire" is fun, too! Animal Kingdom: beautifully landscaped and themed, with Asia and Africa sections. Highlights are the Kilimanjaro Safari, Kali River Rapids ride, "It's Tough to be a Bug" show, live "Festival of the Lion King"', gorillas in several acres of habitat, and beautiful tigers who like to cool off in their moat.
What is proposed specially for the Teens in Florida? Universal's Thrill Rides is great for teens and 'tweens who want to scream. (Disney doesn't do extreme rides, by the way.) The Hulk and Dueling Dragon coasters are guaranteed to thrill. Also not to be missed: The Spiderman "ride", not a coaster but an amazing 3-D simulator experience plus a 4th dimension of surprise sensations. Sister park Universal Studios likewise has great rides based on Men in Black, ET, and Back to the Future, to name a few faves.
The Teens also should visit Universal Studio's Islands of Adventure - one of two Universal Orlando theme parks-- is a fun park which you can tour comfortably in a day. Parents with small kids will want to spend time in the very cute Seuss Landing, based on the books of Dr. Seuss, or in the gigantic Camp Jurassic play zone. Teens and 'tweens will spend the day in an adrenaline rush, hitting the thrill rides throughout the park.
And the whole family with small kids and the teens can visit SeaWorld. SeaWorld (like sister park Busch Gardens) combines fun rides with animal viewing. The Atlantis whitewater raft ride has a huge splash finish, and the Kraken is "the tallest, fastest, longest and only floorless roller coaster in Orlando". SeaWorld is most famous for its Shamu killer whale show, but kids will also enjoy feeding seals, petting dolphins, and walking through a clear plastic tunnel with sharks around and overhead. Shark aficionados can even take a dip in a (well-protected) cage in the giant shark tank. If you have time for it, SeaWorld can even be educational.
Seems, that there is no better place for family jolly vacation than Florida!