The Chicago bike station is fantastic. I've been using it for over a year now. It's a safe, secure place to leave your bike, the attendants and mechanics are fantastic (especially as they get used to seeing you around), and the showers and locker room are clean and modern and well lit.
I never have to fight for a shower on the women's side, but there are days in the summer when the guys' side sees a ton of traffic.
One note, though - prices have gone up a little recently, and the rules for lockers have changed. You used to get use of a locker for overnight storage free with your membership; now you can only use them for day storage unless you pay them $99 for the year. It's also $99 for an annual membership (that's what I have, cheaper than monthly), so for full use of the station it's about $200/year. It's basically about $20 more for the same service I was getting before, when I paid $15/month.
You can use one of their towels for a dollar a day - I typically bring my own. And if you don't want to buy a membership, you can pay a buck or so to use the showers/storage for the day.
If all you want is safe bike parking, that's free in the lower level; members only can use the upper glassed-in levels (closer to the exits, but still monitored).
I'm thrilled with the Bike Station; it makes my commute simple and fast. And there's a kind of endorphin-spike-zen feeling to taking a long lazy shower after a hard ride, and getting to work fresh and happy. =)