I've never been to Lincoln Park Zoo or Chicago. My wife had the opportunity to visit both in 2007, while on a trip to take her now 97 year old grandmother to see her brother there. He passed away earlier this year. We hope to make a trip to Chicago one day, then I'll visit both the Lincoln Park and Brookfield Zoos.
Lincoln Park Zoo is very accessible by public transportation if you stay downtown. Free admission. Parking right now is $17 for the 1st 3 hours. Summer is best but it's also when it's very crowded. Beware of the summer day camp groups during the week but they are gone by 1pm!
Is there a viewing window where you can see the snow leopards without the fence? If so, it looks like this could be a good winter destination for photographing snow leopards in the snow? (Or maybe Chicago doesn't get that much snow, just ice?).
Anyway, if I ever go to Lincoln Park and Brookfield, it would likely be next Fall, not winter, since Brookefield is hosting the September 2010 AZAD conference (Association of Zoo and Aquarium Docents).
The snow leopard is in an outdoor exhibit. It's not large, it was expanded 3 yrs ago, but it provides him (I think it's a male; have to look it up to be sure) with vertical height. It was unusual to see him on the ground because he's usually higher up.
Only the lions and tigers have viewing windows for the public because the rock in front of the viewing window where they lay down is heated in the winter. Visitors can see how huge they are close up.
All of the outdoor big cat exhibits get snow in the winter! The tiger exhibit gets a lot of snow in the winter and they love it! We won't have snow in September, however. Zoolights is going on right now and it's fun to be at the zoo in the winter and at night.
The AZAD convention at Brookfield is going to be interesting. I hope there will be tours to Lincoln Park Zoo but there aren't any docents anymore at Lincoln Park to conduct tours. It'll be interesting to see how they work that out.