I took a lot of multiple exposures in Maine that summer to play with HDR. Some worked well, many not, without getting too far into the "HDR look." The rainbow was actually made into HDR by creating over- and under-exposures from the original photo. Here's one of Harbor Island that's about on the edge.

I don't usually do much either, although I do now shoot in RAW all the time with the dSLR and so can correct exposures and straighten horizons before converting to JPGs. KISS.