The Cross Check is definitely a good bike for your purposes. I realize you're looking for steel, but I'd suggest test riding a Kona Jake if you want something else to compare with the Cross Check. The Jake has STI shifters and is easier to set up with a less agressive riding position.

You probably wouldn't have a problem putting fenders on the ***** Tonk, and 28's are plenty wide for commuting. If you like the ride of that best, you should go with it.