"Are we there yet?" "I wanna Coke!" (or, as my younger brother shouted on similar occasions, "Yer gunna; I'm not gunna"). Tim Clue and Spike Manton's memory-comedy catalogues just about everything ever said during family road trips of yore. What gives the play poignancy: it also articulates what Don Browning - the absent son - left unsaid to his now-departed father. The play and Lamb's Players production begin too over-the-top. Exaggerated squabbles don't prepare the audience for what's to come (amid the din, director Deborah Gilmour Smyth orchestrated impressive, rapid-fire exchanges). Once the two-act show settles in, it achieves a better balance. On Mike Buckley's imaginative set, a raised map of Iowa spreads across the floor backed by a wall of blown-up travel brochures. Led by David Cochran Heath as the kindly dad, Kerry Meads, Colleen Kollar Smith, and Kurt Norby (doubling as young and old Don) illustrate all the symptoms of mobile cabin fever. Paul Maley and the splendid Cynthia Gerber handle the comedy. They change roles - and Jeanne Reith's funny-accurate outfits - often in seconds.