Lewes makes a good base for the Delaware coast. Rehoboth Beach is fifteen minutes south by car or six miles on the bike trail, with the boardwalk and the bigger restaurant scene. Dewey Beach, just past Rehoboth, is the louder, younger beach town if you want a different vibe for an evening. Bethany Beach and the Quiet Resorts are about thirty minutes further south.
The Cape May–Lewes Ferry will get you across to Cape May, New Jersey — a Victorian seaside town with good beaches and a small but ambitious restaurant scene — in about eighty minutes. With an early sailing you can have lunch in Cape May, walk the historic district, and be back in Lewes for dinner.