WITH its picture-perfect canals and waterside palazzi, Venice is a romantic idyll. No wonder 18 million tourists pile onto the floating city each year. But what is surprising is that the embattled residents still manage to carve out a hometown for themselves — a pastiche of in-the-know restaurants, underground bars, quiet piazzas and calmer, outlying islands. And that’s not counting all the cultural offerings that Venetians take full advantage of. The cool art scene now goes beyond the Biennale. And instead of sinking, architectural icons have re-emerged as new landmarks.