Can't help but love that kiss at the beginning of The Palm Beach Story where Colbert's toes curl. Another comes from one of my favorite Sturges films ever, The Miracle of Morgan's Creek, when Betty Hutton and Eddie Bracken go in to "get married."
Finally, I'm going to say the implied kiss at the end of Footlight Parade between Jimmy Cagney and Joan Blondell. The romantic tension in that movie is so absorbing. Got to love the pre-code romantic musical comedies.