You've gotten some good answers so far -
Of course Seattle is a bit smaller than Chicago. Our location in the Upper NW corner of the country means that it's a haul to get just about anywhere else also - Portland OR is about 3 hours away, Vancouver BC is about 3 hours away. San Francisco is a about a 14 hour drive.
The racial mix here will be different from Chicago - I don't know the exact numbers, but we have more Asian and fewer African Americans than the "average" in the country. There is a growing hispanic population also. Interracial relationships are pretty well accepted here.
The greater Seattle area tends to lean left politically. And because we have so much trade with the far east, you'll find more information and focus on Asian trade, culture and news than you'll usually find in the midwest or east coast. We are not very religious overall - there is probably a greater number of people who do not go to church at all here than in Chicago. We don't care if you are religious as long as you leave us alone about our own views.
Recreation - Seattle as a whole is a great place to live. The city is surrounded by water, so sailing, kayaking and boating are popular sports. There are also ski resorts within about an hour drive from downtown (depending on traffic), so you can literally ski and sail on the same day here if you wish. Whistler resort, regularly voted the best ski resort in North America, is about a 5 hour drive from Seattle. Hiking and camping are also big here, with lots of trails in the Cascades and Olympics.
Have you heard it rains here a lot? We have a lot of "wet days", but get only about 35 inches of rainfall a year. It just comes down over 9 long months of fall, winter and spring. Most of the time we don't let it stop us from doing the outdoor activities that we want - we just dress for the possibility to get wet. It doesn't snow much, but when it does, the city shuts down. They have almost no budget for snow plows, and lots of steep streets, so even a little snow can paralyze the city.
And for when it really is too wet to be out, Seattle abounds with great bookstores, movie theaters, a decent music scene and great local theaters. Bumbershoot and Folklife festivals here at Seattle Center are great.
Dining is good. Again, you'll see a lot of asian restaurants - Sushi, Thai, Vietnamese pho and Korean restaurants are all over. There seems to be a teriyaki joint in every strip mall within 20 miles of Seattle. The upper end restaurants tend to focus on Northwest style seafood, which is great. Of course, there is a coffee shop on almost every corner as well, with lots of options beyond Starbucks.
You'll have to search for great pizza in this area. it can be found, but most of it is only so-so. We are still missing a NY style deli anywhere in the city.
Traffic here is awful - we are regularly voted among the worst in the country, so be prepared. Public transport consists mostly of busses, and is OK. Overall crime here is prett low. We seem to get more property crime (car prowl, burglury) than violent crime, and for the most part the city is pretty safe.
Hope that helps!