You should definitely check out Blue 44 DC. They've got specials for New Year's eve 2012. Here's a link to their menu for that night...
Blue 44 DC New Year's eve

Lebanse taverna in Bethesda is amazing with kids and is actually doing a kids new years dinner and cider toast at 4:30. . Check their website or call for details. Cylydes in CHCH is also kid friendly and should have the regUlar menu at that time

Dino was offering a special menu and I think there was a kid's menu up to 6:00 or something

In the past Lebanese Taverna in Bethesda has offered an early regular dinner before they close down for their price fixed new years dining and they are very kid friendly.

Blacksalt if they aren't having special seatings.

Is Clydes too casual?

How about Becks downtown - that is pretty loud and probably shouldn't be busy at 5:00.

Boubon Steak? It is in a hotel, so there will kids dining (there were when I was there).

If it's that early, I doubt it would be a problem having a kid in tow, but you may want to make a reservation b/c many restaurants do special seatings/menus for things like new years and valentines.

I like Jaleo in Bethesda. The foods good and the atmosphere is pretty laid back and a little noisy any way.

We are planning to go out for an early dinner, like around 5pm on New Year's Eve. However, I am worried that too many restaurants will only be catering to adults. I understand why, but we'd still like to take our little one out. Are there any restaurants that DON'T have highchairs in the Bethesda/Chevy Chase/Rockville/Friendship Heights areas? Are there such things as restaurants that frown upon you brining in a small child? And are there any noiser but nicer restaurants you recommend? I want to go to a decent restaurant spot, but certainly want to respect the evening of other patrons. (Not that my child is that bad