One of the best trips I ever had (and a profoundly spiritual experience) was on shrooms while in sensory deprivation. I wasn't in an actual sens-dep tank, but my basement (underground) room was close enough. No light, no sound, 72F, lying naked and still on my bed.
I was flying through galaxies with cosmic lightning bolts surging through my body, which felt ecstatic-- like a "spiritual orgasm." I became One with the Universe and experienced the entirety of space & time. And that's just a small part of it-- the rest is utterly indescribable.
Most of my tripping has been on mountains, in woods, and/or near water. I really dig Nature and I love communing with it anytime, but especially when tripping.
I've dabbled in meditation off&on over the years, with limited results. In the past I was too impatient and too easily distracted to get much benefit. I've recently gotten into it again (or seriously for the first time?) and I'm liking it a lot. I scored some blotter the other day and I'm looking forward to taking it on my next day off. I plan to meditate under the influence and I'll let y'all know how it goes. I haven't tripped in 2 years (shrooms) and it's been a decade since I've taken LSD, so it should be interesting.