I think what the OP is saying is, that because the food (and probably drinks) are at maybe half price during happy hour, what do people tip on? What the full amount of the check would be, or the discounted amount. Like using a coupon at a restaurant where it asks "Please tip on the original amount" or something like that.

OP, your going to get both answers, but yes, I do tip more in this situation. I can't give you exact %, but your wife's amount seems about what I would do.

Cheers.