MADEIRA BEACH — The Tom Stuart Causeway is the gateway to this beach city, taking motorists over the Intracoastal Waterway past a vacant lot, condo complexes and a 1950s-era strip mall with aqua awnings that is home to a tattoo parlor, nail spa, e-cigarette shop and other small businesses. The entrance to Madeira Beach could change dramatically if a pair of Pinellas County developers succeed with plans for those tired properties. Picture three large hotels up to 11 stories tall with 700 new rooms. More than 160 new condo units. New retail development to the tune of 63,000 square feet. New marinas and a dockmaster building. Pedestrian-friendly walkways, a public plaza and an overpass spanning busy Gulf Boulevard. It’s not a vision or a pipe dream. On Wednesday, the city council approved a rezoning of the 5-acre vacant lot at the bridge’s western apron for the Holiday Isles complex, a 548,000-square-foot mix of hotel rooms, condominiums and retail space.