I ran across The Mysterious Benedict Society, by Trenton Lee Stewart. Upon previewing it, I liked it. It isn't necessarily enduring literature, in the vein of The Swiss Family Robinson and whathaveyou, but it is a lively book that fits our criteria for good family reading.
Many reviewers compare it to Lemony Snickett's Series. There are some similarities, not the least of which is the brilliant but lonely orphaned characters thrust into consequential, problematic scenarios outside the scope of your average kid. But where Snickett gets a bit nasty (and profane), Stewart keeps everything above board. And where all of Snickett's adult characters are bumbling idiots or dirty murderers, Stewart's adult characters (the good guys, at least) are intelligent, humble, respecters of children, and deeply concerned with moral issues—while at the same time gently ridiculous, just to keep things hopping. More along the lines of P.L. Travers and Roald Dahl, but even then less dark in the application.
Plus, Stewart takes more than a few humorous pot shots at the Great Society’s method of handling Things. I know how much y’all likes a good pot shot. :D Check out The Mysterious Benedict Society sometime; you know, when you need a break from affecting that British accent required by so many other beloved read-aloudables on your family shelf.