you should check out les claypools version of 2000 light years - i had a grand old time with my friend molly while seeing les play that at a festival last summer.
I've never heard anything trippier than "The Isle of Everywhere" (from Gong's YOU). But I'm still looking.
I would have to say Is this Love or I shot the Sherrif by Bob Marley and the wailers, OMG them songs are soo mellow!
Rollover- String Cheese Incident. Micheal Kang's solo always gets me going. Theres nothin funner that trippin at an incident.
All of dark side of the moon, with 5.1 digital dolby surround sound, 100 watt sub. Its fuckin insane. During the beginnnings of time and money, the sounds keep coming from different speakers, basically circling around you. And/or all of umma gumma, the studio disc. That album will fuck with you. But for a particular song, i would have to say that the second version of "and the day turned to night" by shpongle is the best, played on the setup mentioned above
Pink Floyd's "A Saucerful Of Secrets" is pretty trippy. That'd be a good one. That's cool, but... I think "In Another Land" is trippier.
I love Dark side of the Moon, very dearly. Your sound system sounds awesome, you should try timing it with the sunset. hehe... I like to put in that album right before the sun is going down, or just as it has begun. Obviously, at this point, no lights are on, because they are unnessacary it's sunny! The album goes through it's course, and then after the final heartbeat-like sound effect fades, the album stops spinning. If you time it right, you are all alone sitting in a dark room, thinking, "wow, how'd this happen?" . Last time I did that I rolled on the floor laughing for at least half an hour.. at the album, at myself, at everything, at nothing. I was laughing so hard my mum came into the room and later searched it for drugs. There was none in there... but that album is just great fun!
Back in high school, my buddies and I would smoke to Bone Thugs N Harmony. We would drive around through the backwoods trails at high speed, blasting music and getting high.