Greetings:

Later this year we will be travelling through IAD arriving from Charlotte on US Airways, connecting on to Bruxelles on United in First Class - this is an award ticket

We have a five hour layover at IAD so I thought we would visit the National Air and Space Museum - Steven F. Udvar-Hazy Center located near to the airport.

Our main baggage will be through checked, however we will have a couple of roll-aboard carry-ons. Are there any left luggage lockers/storage facilities where we could leave these for our visit? If not, we thought we would take them through to the United First Class lounge and leave them there (we appreciate that these would be unsupervised and left at our own risk). If we did the latter would we then be allowed to exit the airport? (In the UK once checked in and though security it's not always possible to exit, however past experience of US airports suggests that this should be OK).

Also, should we consider visiting anywhere else during our layover?

Any help and advice much appreciated.