At the time of its completion, Sunnylands was the largest private residence in Riverside County. The Jones design spread across the site in a series of low horizontal pavilions connected by covered walkways, the low profile emphasizing the vast scale of the property rather than the height of any single structure. The compound included not only the main house but guest cottages, service buildings, a nine-hole golf course, a pool, and the gardens that visitors today encounter as one of the estate's primary draws. Jones, who had built a significant practice in Southern California modernism, created for the Annenbergs a building that embodied the post-war California dream at its most expansive.

The Annenbergs used Sunnylands as a center of social and political gravity from its earliest years. Frank Sinatra was married at the estate. Every US president from Nixon to Obama either visited or used the compound for significant diplomatic purposes. President George H.W. Bush hosted Japanese Prime Minister Toshiki Kaifu there in 1990. President Barack Obama met Chinese President Xi Jinping at Sunnylands in 2013 — a bilateral summit that generated significant diplomatic attention. In 2016 the estate hosted an ASEAN summit. The nickname 'Camp David of the West' captured something real: this was a place where the informal became formal, where the social relationships cultivated over decades of hosting yielded meetings of genuine consequence.

The Annenberg Impressionist collection was one of the significant private collections assembled in the twentieth century United States. Works by Picasso, Van Gogh, Monet, and Andrew Wyeth hung in the rooms where presidents and prime ministers relaxed over dinner, creating an atmosphere of casual engagement with some of the most valuable objects in American private hands. In 1991, Walter Annenberg pledged the entire collection — ultimately appraised at over a billion dollars — to the Metropolitan Museum of Art. The works transferred to New York after Leonore Annenberg's death, leaving the house itself and the gardens as the estate's primary cultural artifacts. The collection's departure was a kind of dispersal: the art that had defined the house's interior character now belongs to a public institution.

Walter Annenberg died in 2002; Leonore Annenberg died in 2009. Both are interred on the Sunnylands property, a choice that expresses the depth of their attachment to a place they had built as the culmination of a lifetime of acquisition. After Leonore's death, Sunnylands opened to the public through the Annenberg Foundation Trust, which manages the estate as a center for study and reflection — a mission that formalized what the compound had always been informally: a place set apart from ordinary time, where the business of the world was conducted in an atmosphere of unusual deliberateness. The gardens, designed with drought-tolerant desert plantings, are open to visitors; the house tours operate by reservation.