There is a unique cafe at the Nashua Airport located on the 2nd floor, which is next to the taxiways, and not far from the runway where you can see planes taxiing and if you are there long enough, should be able to see aircraft taking off. Great to see especially if you have kids, they would get a kick out of it !
It is not a big restaurant, and more homey than 5 star, but I found the food to be very good, and they go out of there way to serve you. There are many 4 and 5 star reviews on Trip Advisor, so people seem to be more than happy with the food and service !
It is not very visible, just ask someone and they will direct you ! It is next to the Firestation.