Heres what I want to do for a group of first time trippers. This would require alot of planning and work, but I think it would result in a truely Awesome first trip that would give a favorable color to subsequent trips for years to come.
First, you have to have a fairly big group of good friends, say 8 minimum, preferably 10 or 15. You need to select some people who have some acting talent, with stress in dance and impromtu, and of course they should have tripped several times already (thats not absoutely necessary though, as long as they are good actors they'll play it well).
Make sure two or three of the people will be first time trippers who are pretty calm, collected individuals who you don't expect will be freaking out or anything. Prepaire them for tripping well, discuss it at lenght for a couple of weeks before hand. The idea is to build them up for a truely mind-bending but safe experiance. Don't give any clues that you are planning anything in particular, they should not be aware that you will be doing anything out of the ordinary while they are tripping.
The house should be set up with some rented equipment, a low-lying fog machine, if you can get one (you can rent 'em, or get dry ice and some buckets). The lamps should be set up on X10 controllers, so someone can control them on a dimmer without going over to adjust them.
If you can manage it, add a second or third colored bulb to the lamps without making it obvious. They should be on seperate circuits so that the colors can be controlled seperately.
Of course some blacklights should be set up, hidden up on the walls if possable, just to take the focus away from them.
A movie that has scenes good for taking wippit hits would be good, that way as the 1st timers take whippit hits, you can adjust lighting and stuff while they are in hyperspace.
As the evening starts, people will begin arriving, in regular street clothing. Just hang out, smoke some herb, get everybody comfortable with each other. This is kind of a semi-formal event, as host you will have to kind of control events, make sure people know that things are supposed to be kind of structred, so that everyone will have as much fun as possable, but there will be plenty of time for people to do their own thing too, your not trying to tell them what to do.
Once everone is there, bring out the shrooms or LSD, make sure its high quality Make it orderly, preferably anyone who is tripping will be obtaining the substances from you (and you should know who all is on what, and how much). Make it a bit cerimonial, but no corny. Dose the newbies as high as you think they will handle, and everyone else fairly low. The rest of you are their to make the newbies trips as good as possable, and partcipate in a theatrical event, its not JUST a party.
Once the dosing is over, make a shift in the activities, put on some music, play some group games, keep people interacting (thats the hosts job anyway). This might be a good time to have snacks.
As people start tripping, get out the movie, something trippy, maybe some good anime flick. The choice is important, much of the night will be colored by it, because you will be taking themes from it as acting ques.
Your behaviours and topics of discussion should be scripted to some extent, but not to the point of being artifical, and they should be adaptable to how the newbies might participate.
The plot should involve repeating, but non-obvious patterns of behaviour, and would become more removed from reality as the night progressed. The actors would have costumes that started as regular street clothing at the beginning of the night, and got weirder as things progressed. As the actors got into character, they would quietly slip out of the room every once in a while add apply small amounts of makeup, gradually transforming their appearance.
The lighting would be adjusted at stragic points, over the hours they would shift to strange colors, with track lighting, blacklights and strobe lights taking over as people reached peak. You should plan so that when someone is talking, making a speech as part of a discussion (possably a discussion about reality, the nature of society, religion, whatever, something thought provoking), they will be standing in an area that is lighted by a spotlight of some sort, tracklighting would be good.
When people started to reach peak, the people 'in' on the setup would all be acting very surreal, deliberate, making dance-like movements, coordinated with everyone else.
There would be a thick, low-lying fog generated by dry-ice machines, and possably an air haze (cracked oil smoke preferably) for lighting effects.
If you have lots of real actor-types, you could act out important scenes from movies or plays, Shakespeare and Poe might be good. This would give good excuses to modify lighting and costuming.
For a real mind-fuck, you could have one of the scenes set up where someone is murdered. Then do the Monty-Python thing, and have some other friends, dressed in police or MIB costumes bust down the front door and 'arrest' everybody.