A lot of MDMA, and lsd for who wants to candy flip. Have benzos on hand if you're tripping with a group (incase of bad trips).
Have benzos on hand anyway, and/or some opiate for the comedown. But be careful with people's tolerance here. Don't give both drugs to intolerant users. I'd say give them only opiates OR benzos unless they have a tolerance and are used to combining them. (if you have to choose 1 drug to give to them I'd decide which depending on their anxiety levels I guess, if they are very anxious go with benzos, if not - opiates).