Shrooms.. good.. the rest of your list is bad for your "safe/educated" experimentation plan though. I've tried a few supposedly "safe" drugs (lsd/shroom/x/dxm). I get fairly paranoid on just about anything.
Why omit x from your list? You'd be more likely to die randomly from coke or speed. Not sure if there is any truth to the K horror stories I've heard but by all accounts it is generally not pleasant.
Everyone has different tastes. I didn't particularly enjoy x or dxm (cough syrup, similar to K). My recommendation, is LSD and/or shrooms. I'll just group these since I found them similar. I wouldn't try this unless under competent supervision, a sitter, or at least w/ someone who is more experienced tripping with you at the same time. Some people believe that consuming mass vitamin C will intensify the visual experience, plan ahead if you want to give it a shot. You want to be with someone you trust in familiar surroundings, and you don't want to have to deal with any kind of authority figure 1 on 1. You don't want to get paranoid and have your mom find you and end up in the hospital getting your stomach pumped. After you take it, relax and listen to some music. Wait for it to kick in, let it work for a few hours and smoke some weed after it peaks, it really kicks in the visuals. NOTE: don't mix any hallucinogen with alcohol or excessive caffeine (i.e. pills). Get something to drink (like a soda or juice) or some hard candy. Wouldn't eat anything (noodles will squirm, etc.) Go for a nice walk somewhere outside for part of the experience (leaving anything illegal behind) and avoid fast moving cars (sometimes people try to jump in front of cars for no reason, I saved Redirect's life!). Except to be bitchy as hell the next day, especially if it was your first time.
A good source for more reliable information would be the lycaeum (
http://www.lycaeum.org/) you can find out about side effects, dosages, myths, long term effects and most importantly read about positive and negative experiences others have had. At least you'd be filtering out all the "drugs are bad, don't do drugs mmmmmkay" posts.
-saladami