Stacy,
I feel so badly for you. We just got back from driving to WDW from the Allentown area. We feel like we dodged a bullet...we normally fly and have been using SE quite a lot. But I feel for you and your situation...we were once stranded in FL due to a charter operator going out of business.
Anyway, on our recent trip, we took I-81S to I-77 to 26 to I-95. We left Allentown at 12:30pm, arrived in Savannah, GA at 1:30am...which included a couple of rest area stops, an hour dinner stop at a McD's with a playland, and a 45 minute contstruction delay in Charlotte. It was a great route to avoid I-95 around Baltimore, DC, Richmond, etc. When we traveled to the beach during summer, I-95 S out of DC was still congested at 11:30 at night!
For the return trip, we took I-95 till we got off around Raleigh to visit relatives for the night. We arrived there within 9 hours...including rest area stops and a lunch one. If we didn't visit relatives, we would have gotten to the Wilson, NC area along 95 in the same amount of time. We stayed at a Jameson Inn along I-95 during the summer in Wilson and were pleased with the hotel and the nearby Aunt Sarah's pancake house.
The next day, it took about 7 hours to get to Allentown. We caught I-85 from Raleigh, joined I-95 in Petersburg. For a Sunday, the traffic wasn't too bad...got heavier near the DC beltway, but it kept moving.
In DC, we take the beltway west to I-270, which takes us to Frederick MD. It then becomes route 15, a 4 lane highway which is sometimes limited access and sometimes with at-grade crossings. Doesn't have near the volume that 95 and 83 have. In Harrisburg, we take 581 East (I-83 joins in at next exit) until it joins up with I-81 north. We then take the I-78 split towards Allentown.
We have children ages 5 & 7 who traveled very well. We made 10 minute rest area stops every 1.5 - 3 hours, usually averaging about one every two hours. It's amazing how stiff you can get sitting in a vehicle! Kept ours busy with DVD player, game boys, books and coloring books. On long drives to PA from NC, my teenaged nieces keep themselves busy with listening to books on tape.
Don't fear driving. If you plan it right, it can be very enjoyable.
Hope this helps!