When the doors of the legendary Casa Bonita restaurant on West Colfax opened 40 years ago, Marilyn Carmosino was astounded by the line of people stretching down the block. On Thurday, Carmosino, now 67, sat at a table overlooking the cliff diving pool with her 5-year-old grandson as Casa Bonita celebrated its 40th anniversary. “I come because of nostalgia, and fabulous entertainment for the kids all in one place,” the lifelong Denver resident said. Casa Bonita, draped in kitschy Mexican-themed decor, is famous for the same attractions today that it was four decades ago: a trouble-making gorilla, cliff divers leaping from the top of a 30-foot-tall indoor waterfall, the Old West gunfight and many other trademark features. “Forty years in the world of restaurants is like 400...