Thanks to @ The_Good_Girl for originally putting this list together. If you know of any that need to be changed please let us know.
Restaurant names link to their respective websites, feel free to add your favorite:
Backyard Brewery: the closest restaurant and now a brew pub as well, you can walk across the parking lot.
Red Arrow: the Londonderry restaurant is close to the hotel, good for brunch/lunch.
Airport Diner: hearty diner food, similar to the Red Arrow
Gabi's Smokeshack
Poor Boys Diner
The Stumble Inn
Olive Garden: Italian
99 Restaurant: American
Longhorn Steakhouse: Steak
British Beer Company: Pub
Masa: Asian Fusion
Texas Roadhouse: Steak
La Carreta: Mexican
Yuki Japanese Grill: Sushi and hibachi
Cactus Jack's: American
Yee Dynasty Chinese
Golden Corral
Republic: farm to table
Mint Bistro: Sushi
Firefly: American
Ignite & Hooked Seafood: Seafood and American
Fratellos: Italian
Cotton: American
900 Degrees: Pizza
Portland Pie : Pizza
Hanover St Chophouse: Steak
Red Arrow Diner : American
Consuelo's Taqueria BEST Mexican food in NH!
The Foundry Farm to table
Alley Cat Pizzaria Voted 2017 Best of NH
The Red Barn Diner
KC's Rib Shack
South Willow St - just down the road from KinkyCon. Some of these restaurants get extremely busy Fri/Sat nights so plan accordingly.
Downtown: good selection, but can get very busy - reserve a table if you want to avoid a big wait Fri/Sat night.
Specialty Foods / other