Complex sentence: The lodging chain was founded in 1954 by longtime Chicago restauranter Marion W. Isbell (1905-1988) and a group of investors with the opening of the first hotel on U.S. Route 66 in Flagstaff, Arizona and was headquartered in Phoenix, Arizona.
Split into simpler sentences: The lodging chain was founded in 1954 by longtime Chicago restaurateur Marion W. Isbell (1905-1988) and a group of investors. They opened the first hotel on U.S. Route 66 in Flagstaff, Arizona and set-up their headquarters in Phoenix, Arizona.