We do this trip a lot, and have found that our first choice southbound is usually to take the Tappan Zee bridge around metro NY, and then continue westerly to I-81 south, then rte. 66 (near Strausberg Va) to 17 over to Rte 95.
Having said that, if time is important, Rte 95 is the most direct...or if bad weather then the Rte 95 to the DelMaVa penninsula and then over the Cheasapeake Bay bridge (plan well as there are some low tunnels in Norfolk, VA area) will keep you nearer to the warmer waters and out of the mountains on Rte. 81.
For the most part, the George Washington bridge and cross bronx expressway should not enter your mind...they can be horrible and the cross bronx is the worst road we have ever been on.
If you choose 95, then you have to go around Baltimore and over the John Phillips Souza bridge. Also, don't try to tow the interior route through Washington DC as there is a low tunnel.
All of these routes have advantages/disadvantages..'pm me if you have any questins.....
NHCelt