The term "bicoastal" could mean San Francisco and Boston, but it still usually means New York and Los Angeles.
(Oxford English Dictionary)
1. Concentrated at, taking place on, or involving two coasts, esp. the east and west coasts of the United States.
1939 A. KROCK in N.Y. Times Mag. 29 Oct. 23/4 Bicoastal defense would not, in all likelihood, be required, however, unless the United States was at war with an East-West combination of world powers. 1963 Amer. Midland Naturalist 70 229 Most of these 40 species probably obtained this bicoastal distribution by way of the Isthmus of Tehuantepec. 1991 D. RIEFF Los Angeles i. 27 Los Angeles had been the lesser pole of attraction in the bicoastal custody settlement that had followed my parents' bitter divorce. 1998 Newsweek 1 June 46/2 Everybody girded for a day of bicoastal press conferences in Washington, D.C. and Redmond, Wash[ington].
2. Designating a person who has a home on both the east and west coasts of the United States, or who commutes frequently between those coasts; (also) designating this lifestyle, perceived as fashionable in the 1980s and 1990s.
1978 N.Y. Times 18 June XXII. 1/2 Mrs. Hart..likes to refer to herself and her husband Bruce, director and co-writer of the film, as 'bi-coastal' since they maintain homes in New York and Los Angeles. 1985 Washington Post 17 Feb. (Mag. section) 19/2 She commuted between Washington and Topeka... 'Bicoastal may be trendy,' says Eldredge, 'but semicoastal is for the birds'. 1995 Mojo Feb. 11/1 Beck wasn't just a product of the LA music scene but had paid dues on the New York coffee-house circuit too, becoming something of a bi-coastal beatnik balladeer. 2001 Financial Times 27 Jan. (Weekend Suppl.) p. viii/2 The workaholic from Madrid has become blatantly bi-coastal. As head of both the Washington Opera and the Los Angeles Opera, the super-tenor has transformed himself into a super-impresario.
B. n. A person who has a home on both the east and west coasts of the United States, or who commutes frequently between those coasts.
1981 Washington Post 25 June E1/4 At Musso'swhich is what we aspiring bicoastals call itthey don't even have valet parking. 1992 O. GOLDSMITH First Wives Club xiii. 135 You saw the same people at every soiree: the old money, the new money, the Eurotrash and minor royalty, the bicoastals. 1997 Cincinnati Enquirer (Nexis) 14 Sept. D5 Capt. Muirhead spared a moment for the urbanites among his passengers, especially the bicoastals who consider the bulk of America just something to fly over.