Every Florida tourism ad ever made shows someone out for a solitary stroll on the beach, watching seabirds skim over the lapping waves as the sun lights the sky afire. What greater contentment can there be than a barefoot hike with the sea breeze in your face? Well, OK, there are a few. But a warm and solitary beach is way up there. Trouble is, everybody wants his own patch of sand. That's why 2.7 million people are crammed into Broward and Palm Beach counties. And most of them are lucky to own the sand in their shoes. Still, amid all this bustle, there are still a few lonely spots where the honks and screeches of the city recede to a gentle murmur, lost in the whooshing waves. Tops has got to be John U. Lloyd Beach State Park, jutting out from Dania Beach just south of Port Everglades. There, isolated from the troubles of the mainland, the lucky few can trudge two and a half miles of usually empty beach backed by tangled trees, with only shriveling jellyfish for company. The park is accessible from Dania Beach Boulevard and A1A, 8 a.m. to sundown. Or park at the Dania Beach Fishing Pier at the beach's south end for a nominal fee (open 24-7 for fishermen, until 11 p.m. for everyone else) and just stroll up the strand. Pedestrians and cyclists get into John U. Lloyd park for $1, single motorists for $2, and up to eight people in a car for $4. But that would defeat the purpose, wouldn't it?