I'm not big on store credit cards, but the two I have is Target and Kohl's. Those two are both really are worth having. With the Kohl's, you can count on free shipping and a 30% code about every other week or two. They may send you lower value codes, but you can get the higher value codes on Slickdeals and so far they don't block you from using them. Be sure to sign up for the Kohl's Yes to You rewards program also - that gives you KC too.
At this point, I spend so much at Kohl's that I am an "Elite" rewards member and don't even need the free shipping codes - they just give me free shipping all the time now. This Veteran's Day sale is a big reason I reach that Elite level LOL (But I may be in a "test market" for this version of the rewards program so I'm not sure that is a standard benefit yet)