Attention those from the US/Avid Travellers!

I'm heading to the US in a few weeks
I've already booked most of my trip:
- LA
- San Francisco
- Las Vegas
- New York

I've been to the US before and have been to Washington DC and Florida so I would like to go somewhere new

I am considering Chicago for a few days
Would you recommend visiting? What are the sights that I need to see?

If you can recommend any other cities in the US please let me know!!!