you planning on driving the whole way?
I'd start in Boston -- a very historic city with lots to see and do... Then hop on Amtrak (a choo choo train) to New York - one of the stops along the way is Providence Rhode Island, nice for a day if the weather is nice) Then head further down into NYC... spend a few days in NY -- then back on the train to Philly (one hour from the city) or to DC (3 hours on the train)
Amtrak has travellers type cards that you can purchase a pass for X number of days then get on and get off where you want... (No idea o the pricing, but it should be on their website
www.amtrak.com)
You could then either fly to Florida (southwest airlines has really cheap fares from Baltimore to Most of the vacation destinations in Florida - -though April is spring break time -- the flights will be full) continue on the train to florida or drive.. (it's a boring drive)
From DC you can also tak a train to New Orleans -- and there it's a pretty easy drive to Texas...
Driving in the northeast is a challenge, parking in the north east is a challenge, in most areas you don't really need a car, you can do everything by foot - -and then use the cities public transport-- and take the train to the next destination.