This discussion should probably be moved to the Kohls thread...
Here are my 5 ct: From an accounting standpoint, you need to book in the price you actually pay. So your buy-in is what's on the receipt. Hence, I like buying stuff for personal use with my KC.
The problem with that is that Kohl's base price is routinely (much) higher for stuff than elsewhere and you can't use coupons if you use KC. Especially with the tight window for KC redemption, you often overpay a bit. Hence, for my purchase decision, I value KC at 60%. So if I'm buying something for 100 and earn 20 KC, my mental buy in price is 88. If thats a good deal, I buy.