You may want to prescreen them (I haven't read any of them for years and years) but for kids (of either gender) from ~7-12 yo, I'd investigate:
Patrick MacManus
Piers Anthony (the Xanth series, some of his other work isn't devoid of 'adult' content, and there are some playful references in Xanth, too, but most of it is VERY tame and not inappropriate for preteens... except for the very first book. Unfortunately.)
DD is a kid who delights in humor and humorous writing; some of her favorite books at ages 4-6 were Far Side anthologies, Garfield, Calvin and Hobbes, etc. Jon Stewart and Stephen Colbert both have books, too, if that helps. DD has enjoyed those books.
Some of Cricket Magazine's publications have nice humor in them-- Muse, in particular, DD has enjoyed for many years and has only outgrown, really, in the past year or two (she's 14 now).
