I'm originally from Chicago area and most of my friends are midwesterners. Trust me, you will be very happy here. I would check out Congress Park, City Park, Wash Park, Platte Valley, Curtis Park, Cheesman Park, Cherry Creek, Highland. This website
Denver Uncommon Photography, Your Source for Unique Denver Artwork has great photo tours of these neighborhoods and more. The traffic is not bad in Denver if you live in the city - it's driving to the burbs that is clogged. I really don't think Denver is a party town. One thing I love about Denver compared to Chicago is that when you get together with friends there are more things to do than eat or drink. Go for a hike, go climbing, go snowshoeing, etc... There are fewer trees, but Denver is really gorgeous and green right now. There is no Lake Michigan of course, but there are probably 20 smaller lakes and rivers in the city. I'm sure you'll be very happy. I used to work at Denver Health and they offer great experience and they are definitely right in the middle of the city. Welcome!