I've found that Rockport, Massachusetts, is more affordable to visit than Martha's Vineyard, and offers similar natural beauty.Andrea E. McHughI've loved visiting Martha's Vineyard for the past few years, but it can get crowded and expensive. These days, I prefer heading to Rockport, Massachusetts, a cute seaside town with similar vibes.It has a walkable downtown, similar natural beauty, nice beaches, and a vibrant art scene. I've spent more tha…