Be sure to take into account the ages/sizes of your children, as well as how much "extra space" you need (groceries, sports equipment, shopping, pets...a lot of minivans and SUVs have tiny trunk spaces). Oh, and whether or not flip/fold seats are something that you can get along with regularly if you go SUV. If you plan to keep it awhile you want to make sure it will "grow" with your family!

Taking kids to test drives can be a pain, but before you finalize your purchase it might be a good idea to put everyone in and see what you think.
We have 4 kids and bought a 7 passenger GMC Envoy XL when they were 11, 7, 6 and 4. We loved it at first, but it became a nightmare as they got older....not enough space at all. After acquiring 2 large dogs we decided to upsize with a similar budget last summer. We were trying to find a newer Chevy Suburban without a lot of mileage, but it was pretty impossible under $22,000. We ended up coming across a 2009 Ford e-350 that had less than 3,000 miles on it and a full factory warranty. Not exactly gas-friendly but at least we all fit comfortably.

I like the fact it is fairly utilitarian, just like our Honda Element - no carpet, so very easy to keep clean too. I wouldn't necessarily recommend a full size van if it would be your only vehicle, solely because of the gas concerns. Not to mention, the "look" of it isn't for everyone. It's worked well for our needs with a similarly-sized family, so I thought I'd mention it.
