What do you like to do? What type of restaurants do you like? What type of hotel?

As general information, for a first time summer visitor, I'd suggest:

Stay at any decent-looking or chain hotel in the downtown/loop area.

Visit the Art Institute and the Shedd aquarium, walk or bike (rent a Divvy bike) along the lakefront/Lincoln Park, maybe go to a Cubs or White Sox game (one team will be in town). Definitely take the architectural boat tour on the river.

Try to get reservations now at Girl and The Goat and The Publican for excellent food in casual settings. Lots of high end Michelin starred restaurants too if you're interested. Have a drink on one of the many rooftop bars. Try a restaurant in Little Italy. Look for restaurants with busy outdoor patios.

Contrary to popular belief, Chicagoans don't typically eat deep dish pizza. Skip the touristy pizza places. For lunch try an Italian beef or a Chicago style hot dog.