As you know Chicago is not only a great restaurant city but is a fantastic steak house city.  OK, it all depends when your coming to town and if you can dine alfresco or not.  Either way Lisa is right on the money, Chicago Cut Steakhouse is great any time of the year. They have an amazing outside patio that over looks the Chicago river and fun and social dinning room.  

Bavette's Bar and Boeuf has a great hip vibe designer cocktails. If your into dry aged steak you need to try David Burke's Primehouse. Others to take note of are Joe's Seafood, Prime Steak & Stone Crab, Gibsons Bar & Steakhouse and Erie Cafe. 

We love Chicago Cut Steakhouse - fabulous food and great view of the river, but the room can get a bit loud.  

For something more intimate, Bavette's Bar and Boeuf is great too.

Sounds like you might want a newer place so I cautiously recommend this spot. For an old school Chicago steakhouse, try Gene & Georgetti's Restaurant. Pretty tough to beat. I think the average age of the waiters is like 85. It's a classic. 

For what's hot right now, you have to go to Bavette's Bar and Boeuf. Have a cocktail in the basement (pictured below) before dining upstairs. Also, if you like iceberg wedges, Bavette's has my favorite one.Also, Chicago Cut Steakhouse especially in the summer as it overlooks the river. I'd almost say hit this place for lunch, and Bavette's for dinner!

I'm also a fan of Mastro's Steakhouse, but it's not unique to Chicago. Besides the steaks that melt in your mouth, the gorgonzola lobster mac and cheese is out of this world. 

Gibsons Bar & Steakhouse is just a classic (and close to Morton's the Steakhouse), and Joe's Seafood, Prime Steak & Stone Crab will never upset.

One of my families favorites in the warmer months is Smith & Wollensky - Chicago at Marina City. Sit outside right on the rivers edge for some nice atmosphere. The dry aged steaks are delicious.

Another good spot is Joe's Seafood, Prime Steak & Stone Crab. Clubby atmosphere and always reliable. Really good steaks and seafood.

Chicago Cut Steakhouse gets my vote  

Chicago Cut Steakhouse or Bavette's Bar and Boeuf are two strong candidates.

I really like Gene & Georgetti's Restaurant as we always make a point to visit the oldest restaurant (of a certain genre) depending on our mood, and steak houses are one of them. We'll be there on Labour day weekend and might try Harry Caray's Italian Steakhouse as it's close to our hotel. 

+ 1 for Gene & Georgetti's Restaurant - The very best!

Chicago Cut Steakhouse is the best new steakhouse in Chicago.  It also has great views, being right on the river.

Mastro's Steakhouse or David Burke's Primehouse. Want great people watching with a scratch kitchen with great steak, pork chops sides...Gibsons Bar & Steakhouse

When I go out for steak, I always go to a Morton's, they've always got some kind of meal deal and the food is always excellent.  Chicago Magazine did a writeup on the best last November, not everyone will agree with their choices but it'll give you an idea of the options out there.

http://www.chicagomag.com/Chicago-Magazine/November-2013/best-steak-houses/

I ate at a different branch of The Capital Grille(Rosement near the airport) not long ago, I was not satisfied at all.  Top tier prices, food was good but I still wished I had been at Morton's instead.