Complex sentence: While Reagan spent nearly 1/8 of his presidency at his Rancho del Cielo in Santa Barbara County, California, he also spent so much time at the Century Plaza Hotel in Los Angeles, that the press also dubbed the Western White House for a time.
Split into simpler sentences: While Reagan spent nearly 1/8 of his presidency at his Rancho del Cielo in Santa Barbara County, California. Reagan also spent so much time at the Century Plaza Hotel in Los Angeles, that the press also dubbed the hotel the Western White House for a time.