By "evening dress", do you mean floor length?

I haven't had to buy a floor length dress for some time, but I have bought some nice cocktail dresses online at nordstrom.com and jcrew.com (although J Crew's are a bit more bridesmaid-y, except for the basic black). Both offer some floor length dresses, too.

Since we all are point- and miles-collectors, start from a website like Marriott.com's internet shopping portal (ShopMyWay - 4 MRs per $ spent at Nordstrom), click through to, e.g., nordstrom.com, buy two sizes so you don't have to pay a shipping fee (waived for purchases of $200 or more), and then return what you don't like to the Nordstrom store (or pay a small fee to return by mail). Also, you'll get a wider selection online than in the store.

While at Nordstrom you are unlikely to find a funky or unique style, you will find a good selection for grown-ups, in a decent range of colours, in real-woman sizes, at moderate prices. See, e.g.,

http://shop.nordstrom.com/S/3136660?...esultback=5238