I tried horizontal span, but the resolutions I could select were very limited. All of the widescreen picks were double the normal horizontal number. So I'd see 3840x1600 with no option to pick 1920x1600.

Is there a way I can give myself more resolution options? What I'm running now is my main at 1920x1600 and my 4 alts at 800x600 on the second monitor. All this is with dual view, but in cities I do get enough frame loss that it is annoying. I'd like to run the same resolutions, but in horizontal span mode to see if it improves my framerate.