believe it or not, Saturday is just as bad as any other day of the week. no carpoolers.
Beltway 495 means Western or Outer Loop.
If you have EZPass, there are some HOT Lanes (High Occupancy TOLL Lanes) that will semi-express you from VD/MD line to I95 South at Springfield. maybe $1.35, depending on traffic.
if you want a nice, relaxing drive and don't mind a little extra time, avoid the Beltway altogether and take I78W out of NJ into PA. I81 S to I83 S through Harrisonburg. 581 S to 15 S, through Hershey and Gettysburg, through Frederick, MD (Flying Dog!) through Leesburg, VA (wave to me, I'm about 10 miles to your east at this point)
at Warrenton, VA it gets a little tricky, you're onto a combination of 15/29/17, ending up on 17 and hitting I95 just north of Fredericksburg.
maybe ONE extra hour out of the way, have to deal with a few traffic lights, but it's a beautiful drive and you bypass most of the a-holes on the Turnpike & Beltway
plus, the ONLY toll you pay is 75¢ to get out of NJ, compared to $10 on the Turnpike, crossing the Delaware and Baltimore's Harbor Tunnel