The drive from NY to Baltimore or DC is just long enough to be annoying and a stop for a meal and/or and a stroll en route is well worth the time. Here are a few suggestions:
New Castle, Delaware - the old town is an amazing historical remnant, quite lovely. A couple of upscale restaurants not sampled but locally praised.
nearby Arners Family Restaurant on the southbound side of US 13- just before the airfield. Expanded diner/family style restaurant with strength in their salad bar and pies (ignore the huge mountain sculpted out of margarine on the salad bar and the air-filled bread selection and check out the blue hairs chowing down. the last time we were there, there was a perfect pale yellow creampuff caddy, with pale yellow upholstery in the parking lot. Arners is a branch,I have discovered, of a mini Reading Pa based chain, thus the pies and some of the excellent salads (ex potato salad) on the salad bar, also the wonderful "chicken pot pie" actually a homestyle chicken fricassee with small dumplings (not flat noodles as per Pa dutch "potpie"), a sunday special. I think it was about $6 for this, including good mashed potatoes and the salad bar, terrific value; we took enough home for another meal for two.
Over the Maryland line, Port Deposit is another interesting remnant just a cpl miles north of I-95 wedged between a mountain and the susquehanna- good for a brief stroll (there's just one long street with noble granite buildings in decline) no attractive food options in the town a crab shack (unsampled) on the road into town, the inevitable waterside place next to the inevitable retirement apartments in town next to the river.
Havre de Grace Md is the next exit, and is an extremely pleasant old town, worthy of a longer stop, with several nice B&Bs and restaurants. Of the eateries we tried, we would recommend the Tidewater Grill, in a great location on the waterfront with the predictable seafood, but well prepared, and Chat n'Chew, a long term and idiosycratic local BBQ joint. (the orig Chat & Chew???), with a great soul jukebox. To avoid? - McGregors, with a great location but totally lame brunch chow and service. Maybe something like burgers would be ok, but why bother, with Tidewater right down the hill. The Bridge diner, on the Pulaski Hway (Rte 40) is a classic diner, near the Desert Storm Muffler Man, if you are into roadside attractions. We enjoyed our burgers (nothing special, just good, unpretentious diner burgers) and watched the locals play video poker. Also in that area n. of Baltimore and esp on the Pulaski Hway are lots of "pit beef places", but we had no chance to sample this or try to figure out which, if any, of these places were good.
Finally, just a little S of Hde G, near Aberdeen is Gablers, now closed for the winter, a bare-bones crab place in a peaceful country waterside location, Gablers is very highly regarded in the state of Md. and we liked it a lot too. Gablers is closed now (open April to late September) and has a web site with a useful map telling you how to get there (even with a map its easy to miss).