I really love Denny's. I don't thing a single item on the menu could pass as good, but I still love it.
The interior decor kinda sucks (same with the exterior), the service kind of sucks, and the food especially kind of sucks. With this said Denny's is still fantastic, now I'll tell you why.
The memories. Denny's (at least my location) is open really late, it might even be 24 Hour, I'm not sure.Every time I go (always after a night of drinking) something hilarious or strange happens on a visit to Denny's. In that state, the food is actually highly satisfying and desirable. Generous portions too (as if that matters).
Have a cup of coffee too. I love having a coffee in a proper cup, rather than a to go paper cup.
If it's late, and you just need some greasy recovery food, Denny's is your place.