How to spend 4 days in the Florida Keys and Everglades?

Robbie's in Islamorada is great for kids; huge tarpon (1.5-2M long!) fish hang out at the docks and you can feed them for a few bucks.  Kids love it!

If you're familiar with the drink "Rum Runner" it was invented at Postcard Inn at Holiday Isle.

There is a non-profit sea turtle rescue place a bit further down, The Turtle Hospital, which I'm sure kids would like as well.  

Finally...Make sure you get out on the water.  The Keys have beautiful water and are generally calm out to the reef.  There are plenty of places to go snorkeling / diving if you're up for it, and if not there are always glass bottom boats for you to enjoy.  

Source:  I lived in Islamorada for 2 years.  

Whether or not you stay in Everglades City, if you're headed down to the Keys, definitely plan a stop near Homestead (Florida). The main visitor's center for Everglades National Park is about ten miles outside of town, along with the wonderful, easily walkable Anhinga Trail. (We asked a ranger where the best place to see alligators was - he told us he'd give us a refund if we didn't see one on the trail. We ended up seeing about a dozen.)

Make sure to budget a half hour to grab a milkshake at the Robert Is Here, Inc. fruit stand. So good! From there, you can head for John Pennekamp Coral Reef Sta State Park for snorkeling. While you might want to save snorkeling for another day, especially if you decide to stay on Key Largo, we did all the above on a day trip from Miami.

This will put you a bit off-path but if you love kitsch, it might be worth it. The Weeki Wachee Mermaid show in Weeki Wachee Spring park is a total throw-back to the 50s. Basically it's women dressed up as mermaids performing in a giant tank. Maybe not the best message to send to a six-year-old girl, but maybe you can emphasize the atheleticism. As far as history goes, if you're in Key West, you have to have a drink at Hemingway's favorite bar, Sloppy Joe's Bar, even if it's become a bit touristy. You can also see his home at the Ernest Hemingway Home & Museum. It's such an interesting place but if you're allergic to cats be aware that they roam the grounds as well as the museum--long story but Hemingway had a six-toed cat once and these are its descendants.

The Sawgrass Recreation Park airboat rides are excellent. Around I-75 and highway 27 intersection. You could do that after the drive from Orlando and then stay in Weston (Florida) or continue south to Shark Valley Observatory Tower off Tamiami Trail and stay maybe in Florida City. Mrs. Macs in Key Largo will satisfy your kitschy tastes. Card Sound Rd is a wonderful alternate road to enter Key Largo; make sure to drive it  in one direction.