I'd start with the sway bars only. I changed mine out at least 60,000 miles ago (probably more like 75k-90k) and there is some wear on the inner portion that connects to the sway bar itself (the grease grooves have smooth wear spots).
IIRC, it did tighten things up a little and firm up the ride, but overall, there's little difference (except that the greaseless ones need grease to be added with them removed versus the grease nipple thingy, whose name escapes me).
The other suspension bushings don't seem to get exposed to as much motion, moisture, salt or sun as the sway bar ones. So I'd be less concerned with them rotting. Now if your ride starts to sag towards one end or the other, or if you hear a sudden "clunk"... YMMV
The rear ones were more gross than the front ones - more exposure to salt/brine because of their location. Picked up my set from Summit racing - not the $140 set though.