While I have never driven to FLA, I have driven on I-95 many times in the area you speak of. I am from Philly, and have family in Rockville, MD and Stafford, VA (Quantico). I always take I-495 (the Capitol Beltway), even if i am going to VA (must take it to get to Rockville). I have found that there are always cars around there no matter what time of day, just be patient, and alert. I always get back on to I-95 (not far past Tyson's Corners, a right exit, where many of the cars go, hence the bottleneck). Potomac Mills is exit 156, I think off of I-95, and would be a great quick pit stop for you (run in to the Disney Cat. Outlet in Neighborhood 4 ? near the food court). This is like Franklin Mills, if you are close enough to PA area to have visited that mall.
Good luck and enjoy your trip!