baltimore to cape cod

This might sound difficult but it's not. You should know the easiest way to get on I/78 near Allentown. Take I/78 to PA 33 to I/80 to US 209 to I/84 (at the PA-NY border) to I/90 (Mass Pike toll) to I/495 to Cape Cod. The Newburgh-Beacon bridge is about $10 for us 5 axles and the toll on I/90 is about $3; that's it for tolls. If you take I/287 over the Tappen Zee bridge the toll will be at least $ 20. Also make sure you have an EZ-Pass.
If you arrive between 9 AM and 9 PM at the Cape bridges be prepared for a long wait.