It's always best to call and make sure the outdoor dining section is open. That said, here you go...
We love Bistronomic, about 5 blocks from your hotel
We also love Piccolo Sogno, which has a very popular patio. It's a short bus, train, or cab ride from the hotel
About 7 blocks from the hotel is Siena Tavern
And about 6 blocks away is Tanta (Peruvian, but more than just ceviche)
Beatnik on the River (dinner and weekend brunch)
Jaleo (Jose Andres's tapas place -- not sure about patio, but has seating by open windows)
There are tons of suitable places in the West Loop. For example, on just one short stretch of Randolph there's Little Goat Diner, Bar Siena, and Leña Brava
For breakfast/brunch, on Clark near Frontera, is Beatrix
Also for breakfast not far from your hotel is Edie's All Day Cafe & Bar, but I don't know if they have outdoor seating
True Food Kitchen is right across the street, but I don't know about outdoor seating
Breakfast and lunch near the Hilton (I assume the one on Michigan across from Grant Park): Eleven City Diner
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You also might want to search and/or post on LTH Forum; that's where ronnie_suburban now makes his online home
