When living in SD we were a loyal customer of chef pepper. Loyal meaning ordering a hamburger or 2 at least once a week. It did surprise me though that never anyone has been able to do a better job servicewise. The hamburgers taste great but something is wrong 8 out of every 10 times. No fries, cold fries, no mushroom sauce, wrong soda, small hamburger instead of the big one, too red, or too burned. The fact that I kept ordering was because there wasnt a better alternative.
I must say that now, being back in the province of the Netherlands (as in, not in a big city) I crave for a good hamburger. The only thing here is fries with dutch snacks and shoarma, oh and 'chinese'.
Denny's I think was in front of my brother's in laws restaurant. His place is kind of fancy, and Denny's on that spot looked always kind of out of place to me.