Sounds like a good idea.
Here's a shot of my 5g planted, the main plants are crypts, and the above afformentioned anubias, moss, and ferns.
The foreground plants are hair grass and micranthemum. If you're going with sand substrate, it would be better to use plants that don't take roots, so the crypts, hair grass and stem plants like micranthemum might not be as good to use . . .
I'd suggest making a nice lay out of bog wood in the background and attaching anubias, ferns and moss to it with black thread. Then, take 3 small dark grey river stones and completely cover them with moss, and tie it to the stone with thread again. Arrange these stones in a triangle in the forground. This should give you a nice lay out.
You might also consider moss as a foreground plant, as in the tank in my sig. Sand draws too much attention to itself though, and will make a moss carpet look messy.
Last thing-- neon tetras look great in planted tanks with sand. They're white belly matches the white sand, and the neon stripes enhance the plants.
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