As far as color goes it changes with my mood or the season, for instance I don't generally work with a lot of oranges or lime green but I just made a quilt that pops with both and I love it but its Summer and that is what I'm in the mood for now.
Generally I have a tendency to go more toward purple/blue/green
Like many others have said it is difficult to find a good variety of nice cream on creams,white on white, or off whites, true blacks (things you generally use for backgrounds)
I love a good selection of blenders.
Something that is sadly lacking (none existing really) in my area is 30 repros and Civil War repros and Kansas Troubles or Thimbleberries,
I love it when someone brings in a whole line and not just 3 or 4 because it is much easier to coordinate if you have the whole line to choose from.
Other than fabric I'm always looking at new tools and gadgets.