I too would prefer something enclosed to keep dust off the trains. I really like these cases http://www.showcase-express.co...augeDisplayCase.aspx but there are a few negatives in my opinion. The sizes listed for Standard Gauge are either 6" tall or 10" tall. The 6" tall case is on the small side, could work for smaller sized standard gauge trains but not all will fit and the trains may seem cramped. The 10" case is too big and wastes space, I think ideally the cases should be about 8" tall.
The other negative is that they only come in 4' lengths, you can connect them together but you are still locked into increments of 4', they do not custom cut this size of case.
Lastly, and this is a biggie, the price is sky high compared to the Glenn Snyder type shelving. It would cost an awful lot to fill up your wall with these shelves.
John.