So many choices!!

Well if you plan to run around in the yard, I would consider a vehicle with higher ground clearance, like a monster truck. The friction of the grass on the bottom of the vehicle causes the motor to overheat and prematurely wear or burnout. If the street and school yard are your primary surfaces then I would consider a 1/10th stadium truck or buggy. A stadium truck offers more stability and durability because of slightly larger tires than a buggy. In general buggies and trucks are very similar(brother and sister) sharing many parts.

Depending on how old your kids are, much can be learned from buying a kit and assembling yourself. Especially if you need to make repairs or upgrades later down the road.

You didn't mention nitro or electric. I am assuming electric. But if your leaning towards nitro that is fine. But consider the following: Noise and fine tuning. Noise because of neighbors and the nitro engine requires fine tuning during outside temperature changes. But a REVO would make a for a durable, fun backyard basher.

Regardless, if you get hooked, you may end up at a track or if you don't get hooked you may end up on ebay, either way buy a quality vehicle.