Sanibel and its pretty little sister island, Captiva, form a dogleg of sand that reaches up from the Gulf Coast off Fort Myers, where the leg joins up with the mainland via a causeway. The causeway wasn't built until 1963, sparing these islands much of the high-rise development that has wreaked havoc elsewhere on the coastline.
By the time the causeway did open, Sanibel had been declared largely off-limits to the developers. The pay-off is an environmentally-sensitive island 12 miles long and five miles wide, linked to a second just four miles by half a mile. Together they boast 17 miles of powdery beach and 26 miles of bike trails, all in its natural state save low-rise condos, hotels, shops and eateries folded carefully into an indulgent tropical landscape.
Sanibel has just two main roads that lie parallel to one another. The main drag is Periwinkle Way. Prime stop-off is Jerry's grocery store. Gulf Drive, the other main route, roves past resorts, beaches, and homes at the water's edge. The houses are perhaps one of the islands' most recognisable symbols with their plantation shutters and decorative mailboxes morphed into manatees, flamingoes and pelicans.
The bike paths are so well maintained, and so flat, that ditching the car and hiring a one-speed cruiser is the only way to explore. The J N "Ding" Darling National Wildlife Refuge is home to some 238 species of bird, more than 50 types of reptile, and 32 kinds of mammal. We meandered our way around the five-mile loop of its Wilderness Drive. Passing broad plains of mirrory water, fringed by red mangrove, George pointed out gangly-legged Seuss-style birds and languid alligators basking in the shallows.
Next morning we were back for more. Hiring a two-man canoe and paddled deep into the mangrove forest, we traced a web of ancient Caloosa Indian water trails through a weird landscape of distorted roots studded with barnacles.
One of the planet's most unusual barrier islands, Sanibel's southern end acts like a shovel scooping up all the seashells that the Gulf imports from the Caribbean. It's an island gifted with a swell of shells and an army of shell-collectors. George joined them, shuffling along the sand, doubled up in "the Sanibel stoop". The shell motif adorns everything from door frames to lampshades. Streets are named after shells, and the leading cultural attraction is a museum devoted to them. We escaped lightly with several shell necklaces, a pair of shell-encrusted sandals and an obligatory "look-where-my-parents-took-me" cartoon conch T-shirt.
We hired a motor launch and ventured over to Cabbage Key. We zigzagged through go-slow manatee zones, skimming the smooth blue swells between pods of dancing dolphins. Our destination was a rustic, white-clapboard house built in 1938 by the family of novelist Mary Roberts Rinehart. We ordered lemonade on the screened porch. This is where Ernest Hemingway once liked to hang out. The straight-back chairs and painted wooden tables showed their age, while the walls were so thickly plastered with dollar bills left by past visitors that the whole place maintained an eerie gloom even at high noon. Tacky? Not at all: just part of Cabbage Key's laid-back charm.
The thing that struck George most about the funky Captiva was its glut of blue, bubble-gum ice-cream. For me it was a lack of traffic lights, mailboxes and street lights. One savvy shop owner recommended the Bubble Room for lunch. This kitsch joint is packed to the gills with eye-catching memorabilia from the 30s, 40s and 50s. Its toy trains, twinkling coloured lights and plastic dollies are any parent's diversion-therapy heaven. I watched the customarily picky eater George lick his spoon clean of the remnants of a brick-size slice of lipstick-red Velvet Cake.
In one week I had averaged 12 hours of sleep a night, one trashy paperback a day and half-an-inch round my waist courtesy of every meal. I guess that's why those in the know come back here: that is what they pay for. On Sanibel and Captiva it's possible to pretend that nothing ever changes - save the tides.
Virgin Holidays (0870 220 2788; virginholidays.co.uk) and British Airways Holidays (0870-2433 407; baholidays.com) offer packages to Sanibel. For accommodation, try the Gulf Breeze Cottages on the beach (001 941 472 1626; gbreeze.com). For more information contact The Beaches of Fort Myers and Sanibel (01737 644722; fortmyers-sanibel.com) and Visit Florida (01737 644882; visitflorida.com)