Doha has many great dining options, so feel free to explore the city if you have free time. You'll find fast food, regional and cultural cuisine, and fine dining in the top-end hotels.
Connected to the Marriott Marquis is City Centre Mall, which has a wide variety of shopping and dining options, including Pizza Express, Nando’s, Noodle House, and many other.
Katara Cultural Village, a 10-15 minute drive from the hotel, has a variety of nicer restaurants including Khan Farouk (Egyptian), Mamig (Armenian), and Vesuvio (Italian), as well as stalls where you can eat chapatti and drink karak, a local favorite snack and drink.
For a more cultural experience, there are many good restaurants and coffee shops in Souq Waqif, located 10-15 minutes via car. Some good options at the Souq include Tajine (Moroccan), Le Gourmet (International), Al Bandar (Seafood/Arab), Al-Adhamiyya (Iraqi), Isfahan Gardens (Persian), and more. A local favorite are the many shwarma restaurants found all over town.
Doha has very good Indian food, with some favorites including the fancier Chingari (located in the Ramada hotel), the Garden (vegetarian downstairs, buffet upstairs), Bukhara (at the Khalifa Tennis Compound), and Asha's (Contemporary Indian, located at Villagio Mall). Another favorite experience is the busy Merqab (also known as Al Nasr) Street - filled with small bookstores, rug shops, tailors, pet shops, and several excellent, cheap restaurants. These include Turkey Central, a Turkish restaurant serving excellent mezze (Arabic style appetizers), sandwiches, and grilled meats.