My favorite look on interior is a two-tone leather, similar to the way the BMW M3 / M Coupe have done theirs... I think they are the nicest I've seen to date. Of course, the Ferrari colored bead is always nice looking, too.
Of course, my preference for the Elise would probably be a black sport bucket... in whatever material is lightest. And skimp on everything else. The Elise looks good bare. Why junk it up?