When a place is as far south of the Mason-Dixon Line as South Florida, its slow dancing should pack a little boot, scoot, and boogie. Round Up, which boasts one of the biggest dance floors in the county, is the perfect place for the city slicker set to cast off his Yankee rigidity and learn a whole new way to move across parquet. For the small price of a $5 cover fee, Round Up will teach you the basics of two-step and then turn you loose. Unlike many dance ballrooms that banish newbies to the wall to wistfully watch the preternaturally gifted pros whirl and strut, Round Up focuses its attention on the shy novice with two left feet. At 7 p.m. daily, wannabe rug-cutters line up for a gentle line-dancing lesson, and on Thursdays and Saturdays, couples can remind themselves of the basics of the two-step, swing, and cha-cha from 8 to 9 p.m. But Round Up is no playpen -- experienced hoof-shiners have plenty of space to preen and mince on the spacious floor. Good thing four full bars ring the dance floor, making it easy for a novice stumbler to refill on a little liquid courage before giving it another go.