Hmmm...It's been a quite a few years since I lived there but I'm happy to share with you what I remember.
If you're coming in on 17, there is a decent Mexican restaurant at exit 122. Make a left onto E. Main Street and follow that a couple of miles. Should be on your right around Schutt Rd.
If you're driving in on 84, take exit 3 and follow 17M to Dolson Ave. On your left will be a strip mall with two good restaurants -- The Corned Beef Factory for excellent and authentic Jewish Deli and the other (I'm sorry I don't recall the name right now) is a small Italian Food Store/Deli. There's no place to sit down but everything is fresh and homemade. Try their Squash Parmigian -- it's awesome.
On Route 211 -- which is Middletown's "Strip" -- I used to enjoy Cosimo's, which is right off of exit 120 on Route 17. It is right off the highway on the right as you're heading towards Montgomery.
If you're in the city of Middletown, try Tony Boffa's, an Italian restaurant on E. Main Street and Railroad Ave.
There are also any number of Diners in the area. I like the Americana on 211.
Except for the Corned Beef Factory and the Italian Deli, none of these places are going to scale to any culinary heights. Still, any of them are way better than any chain restaurant you may eat in otherwise.
Good luck and enjoy your one night in Middletown!