I used to use benzos and smoke some weed, it always worked perfectly. This was for ecstasy and meth comedowns.
Now that my tolerance to benzos is too high it is never 'enough' so I'll usually have to take an anti-psychotic like seroquel to sleep. But usually I'll drink lots of water, take some vitamins, smoke some weed, maybe have a few drinks (alcohol), eat some benzos and take some seroquel to fully kill the comedown and make me sleep. Speed comedowns take alot to 'ease' for me these days.
In regard to psychedelics like LSD, I generally just like to smoke weed, drink beers and maybe have some benzos but it's not really needed. Depends on the situation but I've never wanted to take an anti-psychotic on the tail-end of a trip, that'd ruin things a little unless I just desperately wanted to sleep.
But for uppers like meth or d-amp, a cocktail of valium and seroquel usually does the trick, and if I have weed that just makes things a whole lot easier too.