My sister and I are going to DC, and one night we want to get a little dressed up and have a blow-out memorable dinner, price (almost) no object. We don't want to go to Georgetown, or very far afield from the Mall, where we'll be most of the time. Any suggestions for an atmospheric place we can wear high heels, and eat outstanding food, in the downtown or Mall areas?

The Caucus Room may be the place for you. In the "Penn Quarter." Plus, if Congress is in session when you are there, whether you know it or not, you are rubbing elbows with members of Congress and lobbyists.

For great (maybe the best) and expensive food, I'd say Galileo. More like downtown (west end) than close to the Mall. But this too would not disappoint.

Those are 2 great suggestions, but there are countless more. The funny thing about DC is there are tons of upscale restaurants - while dress at these places can range from casual to business casual to formal at the same time. DC's upscale restaurant goers are a combination of tourists, conventioners, and lots of people straight from work in a town where suits are still worn.

Have fun!

As jp36 said there are many good restaurants in DC. A couple others to consider are Kinkeads on Pennsylvania Ave is great http://www.kinkead.com/kinkead/kinkead.htm
or a newer place is Indebleu near the MCI Center http://www.bleu.com/indebleu/
Enjoy yourself

You might also want to consider CityZen in the Mandarin Oriental Hotel. It's on the waterfront, not far from the Mall (you'd probably want to take a cab though). It's one of the new hip spots in DC for fine dining and I've had two wonderful meals there.

Or for (I think) the most memorable dining experience DC has to offer, make a reservation at Minibar, housed in a restaurant called Cafe Atlantico in Penn Quarter (very close to the Mall). It's a 6-seat bar where you are served between 30 and 35 small courses by 3 chefs who will entertain you for hours while you watch them prepare everything. It's really unbelievable and I think the fun and most unique experience you could find here.

Thanks, all. Great ideas. -travelling

Unfortunately, most restaurants don't seem to care about the dress code but a few do and normally at the following restaurants people are dressed nicely with men in suits....most of the time.
Charlie Palmer's Steakhouse on Constitution. Has good selection of beef and seafood.
Kinkead's has 99% seafood. Very limited selection of meat.
The Capital Grille - chain restaurant but not to bad and is on Pennsylvania.

All of these have websites to check out
Make your reservation ahead of time and no earlier than 8:00PM for a more active night.