It all depends on your financial situation. There is very few true ski in/out lodging (if you are into that) at Mammoth, and it's very pricey. However, the money you save driving a family vs flying a family may even that out. However, Mammoth will be extremely crowded at times you can normally take your kids for more than a weekend, especially if they have to stay on the lower mountain. If everyone can handle black/ double black diamond terrain, there are a few chairs that never get huge lines.
However, check out June Mtn. No ski in/out, but relatively inexpensive lodging, a really fun mtn (unless you are hardcore), and very few crowds, even on holidays.