My favorite rc for stim comedowns is jwh-018. Taken with melatonin, it helps me relax and get to sleep. It has the added bonus of actually making me feel great during the comedown if I take a (relatively) high oral dose. I haven't tried many of the new ones, but I'm sure some other rc cannabinoids would work too.
I hate the way benzos make me feel, but some people seem to like phenazepam for stim comedowns.