The first thing I thought of was Terry Pratchett's Discworld, in which the Rim is a great fall of water that shimmers with all the colors of the spectrum. Pratchett's spectrum has eight colors -- the eighth is octarine, which only wizards can see.
If you've not yet read him, I highly recommend you give him a shot. His books are brilliant.
Oh -- and the Discworld is carried on the backs of four elephants named Berilia, Tubul, Great T'Phon, and Jerakeen, which stand on the shell of the great A'Tuin, a giant turtle who swims slowly towards the center of space. ^_^
I personally like Pratchett's version of the Rim, although I believe our edge would be somewhat different. I think it would be a great oceanic circumference, as it is in Pratchett's interpretation, but were the Earth to be flat, I believe that the waterfall itself would alter in appearance with the rotation of the Earth. Moonlight would influence the waterfall and fill it with lunar light, perhaps creating something to a lunar corona. It might even shimmer with reflected stars. On the other hand, sunlight would create a plethora of rainbows and golden streamers. It would be entirely amazing.
I have trouble determining what the temperature would be like overall, because I can't imagine an orbit of Moon and Sun being at all similar with a flat Earth. I imagine that the days and nights would be pretty equally divided, since the days and nights at the Equator are almost precisely 12 hours apiece. I think it would be some evenly divisible number.... but it seems to me that our days and nights would be rather shorter given a flat Earth. Maybe I'm totally wrong, but it just seems that way to me. I can't help but think that a flat Earth would be warmer at the edges and cooler towards the center.... perhaps even tropical to ice, with allowance for elevation above edge-level for specific locations.
Thank you for this question!