The Adler actually does rent out for events.

The ride to Wrigley from downtown is fine. You need to get off at Addison on the Red line, not Addison on the Brown line. Check on the platforms (or www.transitchicago.com) for bulletins on the red line. It has been running above ground on the Brown line tracks at night alot lately.

Depending on where the bar you're planning to visit is, it is entirely possible that the Brown line Southport station or the Brown/Red line Belmont station may be closer - you can check Google maps and select the transit option under directions for bus/train routing.

The only two lines which run below ground (subway) are the Blue and Red lines. If you don't want to ride the Red line subway to Wrigley, take the brown line to Fullerton and switch to the Red line as it runs above ground at that point.

You will be able to enjoy the downtown views taking the brown line to Wrigley via Fullerton. You want to be on the right side of the train coming out of the loop. Once you pass Chicago you want to be on the left side for the portion between Sedgwick and Armitage. Beyond that there's nothing to see really. I think the brief segment between Sedgwick and Armitage is the best on a clear day.

The machines at the airport will take plastic or cash and sell day passes, multiday passes, and just cards with a set value.