Movies that make a point of insisting that families are big, loud, crazy, intrusive, necessary things tend to be as obnoxious as the bickering clans they’re about. The Daytrippers has some of the wacky dysfunctional chic that made David O. Russell’s Flirting With Disaster such a grating experience, but writer-director Greg Mottola has a lighter, warmer touch; his characters don’t have to act like pigs in order to prove they’re human. Hope Davis, whose slightly ditsy cuteness is fast making her the Teri Garr of independent film, plays a Long Island housewife who thinks that her husband (Stanley Tucci) is cheating on her. So she piles into a station wagon along with her mom (Anne Meara), dad (Pat McNamara), sister (Parker Posey), and sister’s boyfriend (Liev Schreiber), and they go on a wild Manhattan goose chase to locate the suspected betrayer. Most of the cross-generational strife is tiresome (Anne Meara squawks like a dimmer Edith Bunker), but Mottola writes tart and funny dialogue for his own generation. He keeps the action flowing and gets lively work from Posey, Campbell Scott (as a downtown lit-world stud), and Schreiber, who plays a self-adoring loser with exquisite smugness.