Reading through this I get the feeling you'd be happiest with the RC18T's as well. We have (or have had) one of almost every major brand car out there and the 18T is the only mini that's still fun to bash with outdoors. Mini-t's are too fragile, 1/10 scale are too big for the driveway.
The 18T seems to get through everything but tall grass with ease and I like the complete package deal for what, about $189? The chargers they come with are really slow so plan to get at least one decent charger and a couple extra packs. 2 packs per car should be fine, running the same area for 20 minutes gets old.
As a bonus they work really well on ozite carpet tracks with a simple change of tires to foam, in case you ever decide to go racing.