I'm not sure exactly what you're going for cuz i find that alot of art becomes quite psychedelic when i've taken psychedelics, I am a huge fan of alphonse mucha, check out Andrew/Android Jones, martin french, Alex Grey is a must, I'm particularly fond of a Graffiti writer by the name of ZEDZ, also SABER, DAIM. I also think that everyone should be able to find something they like in H.R. Giger's work, even if they're not inclined towards darker imagery, his work has an often replicated, never duplicated style that has produced some of my favorite images.