Mr. Romney is expected to pull in $3 million from an event at the Creeks, the estate of Ronald O. Perelman, the billionaire financier and Revlon chairman, where tickets range from $5,000 for lunch to $25,000 for a V.I.P. photo reception. Another will be held at the home of Clifford M. Sobel, an ambassador to Brazil under President George W. Bush, and a final dinner will take place at the Southampton estate of the billionaire industrialist David H. Koch, where the going rate for entry is $75,000 a couple and $50,000 a person.

Mr. Romney’s campaign seeks secrecy when it comes to its fund-raising events, but organizers suggested that these would not be the showstoppers of the Democratic events of yore. As one member of his finance team put it, “There’s enough interest in stopping Obama that you don’t need to hire entertainment and celebrity chefs.” Besides, the real estate should be entertainment enough.

At Mr. Koch’s estate, the guests will be treated to one-of-a-kind scenery as they wait for face time with a possible president. Tucked into the Southampton dunes, Mr. Koch’s home is valued at about $18 million by the real estate Web site Zillow, which reports that it has seven bedrooms and nine bathrooms. Its backyard is the sea.

But the jewel of the day is Mr. Perelman’s. With 9 fireplaces, 40 rooms and an expansive wine cellar, his estate makes the Koch spread look modest by comparison. Sitting on 57 acres, it was built for the painter Albert Herter in 1899, and when it last went up for sale in 1991 (for $25 million), The New York Times described it as “the largest and most spectacular estate in the Village of East Hampton, with more than a mile of frontage on Georgica Pond and a view of the Atlantic Ocean beyond.” That article also said that an American Conifer Society Bulletin — for tree enthusiasts — had called its grounds “the eighth wonder of the horticultural world” and “the most outstanding private conifer collection in the United States, a living work of art.”