Sorry if you're already done, but I found something that would look AWESOME.
Do a seach locally for "3M Colorquartz" I believe the type S is more like sand. The particles are 1-2mm in size, and basically sand coated with ceramic. (completely inert, I've read about entire forums that switched to this as a substrate) I plan on getting it as a cover for my 50G.
It's useful because:
1. it's cheap- $20-$25 for 50 Ib's
2. Lots of colors available... You can create some really nice blends- it's available in 16 colors.
A blend of 1 part buff, 1 part white, 1 part brown, and 2 parts tan would look nice.
Keep in mind also that fish show their colors better over a darker substrate most of the time. The soil in the amazon, for example, is a bright red, but it's covered with layers of silt and plant debris so it's really more of a darkish-brown/black.
I plan on getting mostly black, with a touch of red and brown if I can find a small qty of them. If not, I'll use some small pebbles on top of the black sand to give it depth (imo)