To be honest, I'm not sure at all about the history of this diner or even what it was called at the time they filmed FWWM. It's now the Fall City Grill, located just down the road from the Roadhouse exterior in Fall City, WA. Given how little they changed about most locations for the pilot and film, I imagine that most of what we see in FWWM was how the diner actually looked in 1991.

It seems that sometime between '91 and 2000-something they turned it into a full-throttle sports bar and restaurant.