Suggest a color film that's one step better than Kodak Gold or ColorPlus?

Back to the original query, I didn't see @dcy specify color negative film, in the original post. That being said, I would recommend Kodak Ektachrome E100. It is easy to obtain, and the fine grain is a definite advantage, with the half-frame format. I would think, with a proper drum scan, you could really "wring" quite a bit out of half-frame Ektachrome.