We do "something to eat, something to read, something to play with & something they need". It makes it easy & keeps me from going overboard (except on the eat part LOL). I just told my 22 year old my formula & she was shocked - she had never realized that I did that! LOL
I find it is minimal waste - food gets eaten, we get "keeper" books whenever possible (or special magazine subscriptions), something they need is obviously not going to be trashed, so the only questionable item is something to play with, but we try to really target each person. Crafty kids might get supplies, musicians can get something for that, gamers might get a remote they want or a game, our teen dd usually gets make-up.