The best place for front jackstands is right under the front radius arm bolts, if you aren't working on the front suspension. If you need to hang the suspension, the best place is on the frame right behind the bumper (you will of course need higher jackstands for that). It helps stability to keep the front stands as far from the rear ones as possible.
There are similar placement issues for the rear -- the best spot is between the U-bolts, and the frame ahead of the rear bumper is an alternative.
The radius arm ought to hold the weight of the vehicle, though it wasn't meant to under normal circumstances. The radius arm bracket can easily hold the vehicle, though there is quite a lot of weight ahead of all the jackstands if you do that.