The Westin provides 24hr room service, and there is also an American-style restaurant called Nourish that is open for breakfast, lunch, and dinner, although reservations are recommended, $$-$$$

Within 5min walk:

Starbucks: Iconic Seattle-based coffeehouse chain, $$
Loughmiller’s Pub & Eatery: Lively spot for American favorites, $$
Subway: Build-your-own sandwich chain with some vegetarian options, $
Café Patachou: Modern yet comfy breakfast and lunch spot with vegetarian/vegan options, $$
Dick’s Last Resort: Southern eats and a salad bar served by surly staffers who accept reservations, $$
Steak ‘n Shake: Diner like chain for burgers and milkshakes, $
Ram Restaurant & Brewery: Pub food and craft beer chain that is popular for solo dining, $$
Mikado: Breezy sushi house for fusion dishes with healthy/vegetarian options that accepts reservations, $$$
Palomino: Italian eatery with a notable happy hour and healthy/vegetarian options that recommends reservations, $$$
Ruth’s Chris Steakhouse: Upscale American steakhouse chain that recommends reservations, $$$$
P.F. Chang’s: Sleek chain with twists on Chinese fare, $$

Within 10min walk:

Yard House: Upscale sports bar that accepts reservations with many draft beers that serves healthy/vegetarian/vegan options, $$
Nada: Colorful stop for Mexican favorites that serves healthy/vegetarian options and recommends reservations, $$
Harry & Izzy’s: Modern twist on an old-school steakhouse that recommends reservations, $$$
St. Elmo Steak House: Ritzy landmark for chops and seafood, $$$$
Primanti Bros: Sandwich chain with piled-high creations, $
Weber Grill: Relaxed steakhouse with warm décor and healthy/vegetarian options that recommends reservations, $$
Panera Bread: Bakery/café chain with healthy/vegan options, $$
Buca di Beppo Italian: Chain serving family-style Italian fare that accepts reservations and offers vegetarian options, $$
Giordano’s: Chicago-style pizza chain with vegetarian options that recommends reservations, $$
Hyde Park Prime Steakhouse: Upscale steak and cocktail chain that recommends reservations, $$$$
Champps: Convivial sports bar and grill chain with a salad bar that requires reservations, $$
The Capital Grille: Upscale chophouse chain with clubby look that recommends reservations, $$$$
Sugarfire Smoke House: Rustic option for BBQ and spiked shakes, $$
Aubonpan: Bakery/café chain for soups and sandwiches, $$
South Bend Chocolate Café: Hot drinks and treats with outdoor seating, $$
Greenleaf Juicing Company: Organic and family-friendly with healthy/vegetarian/vegan options, $$
Potbelly Sandwich Shop: Casual chain for toasted sandwiches with healthy/vegetarian options, $
Soupremacy: Place for seasonal soups, salads, and java that is popular for solo dining, $
QDOBA Mexican Eats: Counter-serve Mexican chain, $
Chipotle Mexican Grill: Chain for build-your-own Mexican fare with vegetarian/vegan options, $
Five Guys: Fast-food burger and fries chain, $$
Buffalo Wild Wings: Sports-bar chain serving American fare, $$
Napolese: Stylish gourmet pizzeria with cocktails and vegetarian options that recommends reservations, $$