That mistake is going to cost you about 5 G's I'm afraid, with depreciation and fuel prices. The less economical vehicles aren't selling nowadays and your trade in will be minimal.
With 2 children, safety would be paramount for me. Most people have tunnel vision these days when buying a new vehicle... all they can see is MPGs.
I don't know what your budget is, and I prefer large/heavy duty for safety's sake... but if I had the money and small children, I would seriously consider Volvo. Their safety is nearly unmatched and they're quite economical to operate.