I have a friend who rents out RC cars at events. Short course trucks (2WD) are great as they are very strong, the shell protects the drive train and they also look more realistic than buggies. He also does TT01's for inside but the short course trucks are so popular he usually will now do these indoors.
the other thing is to run them with 4cells not 6 cells, they are still fast but not too fast and this will avoid a lot of breakages and is also easier for people to use.
TRF419, TBEvo6, TT02, VDF, TRF501x, TRF201, TRF101, Mi5, X-Ray T4-13, BD7 2014, A700 Evo, WR-02G