First of all, I'm 20, and didn't even drink until I was almost 19. I considered pot completely out of the question up until the first time I did it out of curiosity (I wasn't at all pressured into it, but it was available, so I tried it).
I smoke pot fairly regularly and plan on continuing that trend. I don't like smoking too much because I get kind of numb to it (I was high for the past 5 nights and it stopped being nearly as fun), so I plan on limiting it to once or twice a week, max. Sometimes I drink when I smoke, usually I just hang out with friends and listen to music. Once I had a full-blown trip while smoking, not sure if it was the atmosphere or if it was spiked or what, but my vision fragmented into crystals, I stopped comprehending language and reality, didn't understand why people did or cared about anything, considered existence terrifyingly absurd on every level, and felt like I was stuck in stasis in a four-dimensional sculpture. I haven't had an experience like that on pot since, but I felt similar feelings (albeit much more positively) on shrooms and salvia.
I took Ambien legally for insomnia, but still had a lot of fun tripping on it. First time I took it, I felt like I split into two separate people, so instead of just me there was myself and a laughing woman standing just outside my vision, and I was somehow both of them simultaneously. When I finally went to sleep I felt myself split apart into a thousand tiny stars and float around my bed. Not sure if this counts since it was taken legally for medical purposes.
I've smoked salvia once, mixed with a very small amount pot, and had a very strong trip (transported to a cartoon land with talking refrigerators and singing birds) that peaked for about 15 minutes, and took an hour and a half to completely cool down.
A few months ago I did shrooms for the first time, half an eighth of a very potent strain, temporarily forgot absolutely everything (I was still intelligible, and reportedly fairly normal, but I had no idea what the words I was saying meant) and spent a few hours relearning what it meant to be human. It was a bit frightening at times, but coming down from it was the most refreshing feeling of my life, and the positive effects of the experience are still lingering. Also, now whenever I smoke I get mild closed-eye hallucinations of colors, fractals, and shifting tiled patterns.
I plan on doing shrooms again sometime this summer, and after that (when I think I'm ready) mescaline and LSD. I don't plan on ever recreationally taking a drug that is addicting, possible to OD on, or that is known to cause long-lasting negative effects. From what I've read, psychedelics (and marijuana) don't pose any medical dangers and are much safer to (with proper precautions, sitters if necessary, etc) than alcohol. I don't like even referring to pot, shrooms, etc. as drugs since there's a world of difference between them and their effects and something like alcohol, nicotine, caffeine, or cocaine.