You might be able to find some flounder wade fishing the bay side of Cape Henlopen. Flounder will eat clouser minnows pretty aggressively. The ocean side has a few rock jetties that might be a good place to cast a fly rod from.
I've also had good luck with Bluefish and shad at Indian River Inlet on moving tides but they are usually feeding in the current rip which is well out of fly casting range - I needed a heavy spoon to reach the fish with spin gear.
I've seen pictures of schoolie stripers caught in a place called Canary Creek near Lewes, but it looks like you need a boat to fish that area.
Don't overlook the freshwater fishing in Delaware in the weedy mill ponds. I had an enjoyable day there last weekend kayak fishing Burton Pond, catching 3 bass and 4 pickerel in under 2 hours of fishing.