Hotel art doesn't have to be bad copies of "Stag at Bay" on every floor. At the beachside Cadillac Hotel in Venice, a French artist has done up the lobby in his "Venice Renaissance style," a cosmic explosion that, says artist Thierry Bernard, could resemble "the end of the world, or beginning of a new one." With muraled walls and ceiling, mirror-adorned plastic strips hanging like stalactites, and 25 vari-painted TV sets--none of which work, says Bernard, happily--the lobby of the 30-room hotel, with its $10-per-night share-a-room plan, draws young travelers from all over the world. Still in residence are a dozen or so original elderly tenants from the Cadillac's venerable days as a residential hotel. Lest any guests forget where in the world they are, Bernard has floored the lobby with sand. "It's practical, and it's comfortable. Like the beach."