I second Felice's recommendation of the Hotel Colon. It was very comfortable, the people were friendly and helpful, and (for my likes) it has the best location in the city.

Even if it's seems booked, why don't you try checking availability every now and then with the hotel, or ask a travel agent to work some magic. I sometimes have success by being persistent and attentively patient. On the other hand, if there's a convention or some such in town at that time, all bets are off.

Joel, Chicago