No one with any experience with DC traffic would take 270 to a destination south of Richmond VA. Depending on starting point and destination preferred routes are I-81 and US 15.
Some of the improvements that may take traffic off of 270 include: Improving MD-97 to four lanes all the way from Westminster MD to Silver Spring MD, building the Brookville bypass. Upgrading the Point of Rocks bridge to 4 lanes (or even 6). Adding several trains a day to the Brunswick MARC Line, likely requiring triple tracking the CSX Metropolitan Division as impacting freight capacity is not a viable option.
Remember that all of those people driving on 270/495 also need to get off the interstate and find a parking spot.
If I have to do vaca travel out of D.C. during the week, I leave between 3-4 a.m. You have no choice.