Few musicians ever successfully develop dual careers doing adult songs and kid stuff. (Not even jazz composer Fred Rogers.) But L.A.'s GWENDOLYN has released two CDs on her Whispersquish label destined to appease both art-pop aficionados and preschoolers. For postcollegiates, DEW offers abstract meditations on obsession amid a psychedelic-acoustic cabaret that suggests Sam Phillips borrowing Tom Waits' bottle-banging percussion. Even when she sings of being swallowed up in some ill-chosen lover's void, Gwendolyn maintains a sense of wonder about the whole consumptive process. Said wonder blooms more fully in GWENDOLYN AND THE GOOD TIME GANG, in which she and her side-project band celebrate sharing, baths, good manners, and monkeys. From ''Farm Animal Friends'' (a rival in catchiness to ''Old Macdonald...'') on, it's as good as tot rock gets, and a tonic for grown-ups who miss Jonathan Richman's midperiod infantilism.