If you want to take advantage of your elite perks & the hotels you're considering have exec lounges, check to see if the lounges will be open during the 26th-30th. Some properties close their lounges during the Xmas holidays because bookings are down/less biz travelers. That might not apply in Chicago, as it's a pretty popular destination, but definitely something to consider.
If closed you would still be entitled to breakfast (don't forget to link your SPG/MAR accounts if you haven't done so, as SPG doesn't provide brekkie to Golds but MAR does).
Cheers.