Malibu Maxx, Mazda 5, Mazda 6 Wagon, Taurus/Sable Wagon, Escape/Tribute/Mariner, Aztek/Enclave, would all likely work pretty well for you.
The Focus and Mazda 3 5-door would probably be OK, too, but a bit smaller than those listed above, and you would also do fine in a Camry/Accord/Altima/Fusion/Sonata/etc. sedan. The ex-wife and I had a Galant and a Mercury Tracer with a 3-year-old and a newborn, and never had problems hauling a double stroller and every other thing you need with two kids.
A first-gen (98-03) Toyota Sienna with documented oil changes every 5k or less would also work in your price range, especially if you plan on having a third.