To Gillian on Her 37th Birthday

To Gillian on Her 37th Birthday is an emotionally jam-packed experience: Not only is Dad (Peter Gallagher) always out on the moonlit Nantucket beach cavorting with Mom (Michelle Pfeiffer) despite the fact that she's been dead for two years, but their daughter (Claire Danes) is contending with teenage sexuality and a conflicted desire for independence. Now add meddling in-laws (Kathy Baker and Bruce Altman) who try to set the grieving widower up on a blind date even while avoiding the possible dissolution of their own marriage (exacerbated by a comely young thing in a thong). Then again, given the script's klieg-lit straining toward ''contemporary wit,'' maybe it's not jam-packed so much as empty. Although it's a gyp at theater prices, the contrived romance goes down more easily now that it's easier on the pocket. B-