Hi Steve,
Everyone has given good advice so far. I made the trip from Croydon on my 27' all the way down the Delaware, through the C&D, down the Elk River, then back up to Havre De Grace two years ago. While it seemed quite daunting at first it wasn't bad at all. Obviously mind the commercial traffic, especially once you pass the airport. Keep an eye on the weather, the Delaware Bay can get rough. I would suggest passing Pea Patch island on the eastern channel and then make the right turn into the canal once you are directly perpendicular to it. Don't try and cut the island and come into the canal at an angle.
Once in the canal you can stop at Summit North Marina which is about 1/2 way through and grab a bite to eat or make it to Engineers cove which is most of the way through. I went through at night and there are lights all the way through which make it easier to see commercial traffic (they block out the lights like an eclipse!) Once on the Elk it is a nice ride down. Past Turkey Point the bay really starts opening up but stay towards the Eastern Side all the way down until you pass Pooles Island, otherwise you may wander into the restricted area.
Another good spot to stop to anchor is Fairlee Creek but the entrance is tricky. You can also anchor behind Hart Miller island. There are a bunch of marinas in Middle River with restaurants that you can stop at also.
Watch your weather window and always have your vhf on. Also, Noaa has free charts you can download in booklet form, you can print them out on your home printer.
Manny