There's a Lou Malnati's within walking distance of the Field Museum. It has pizza, pasta, salads, etc. There are also several tapas restaurants, a New York Deli restaurant, several excellent Thai places, and an old neighborhood Italian Trattoria that's relatively cheap (for Chicago) that's a couple of blocks farther.
The Gino's East downtown is on Superior St., east of Michigan. It has pizza that some consider to be the best in Chicago; it also has salads, sandwiches & pasta, stromboli and many other choices. Here's the link to the menu:
http://featuredfoods.com/a-store/gino_p3a.pdf It's very easy walking distance from the Drake. Sorry, I keep saying walking distance without factoring in people who may have mobility issues--the Lou Malnati's would be about 3/4 of a mile from the Field and Gino's East is about half a mile from the Drake. Trattoria Caterina is a good mile. It is a quiet place, with pizza, pasta and Italian dinner items like chicken vesuvio.
I would suggest that you make a tentative reservation wherever you're going, if you decide on Thursday.