Female sex workers in SF

• Aldiss, Brian W. "Lambeth Blossom" in Strange Bedfellows: Sex and Science Fiction, edited by Thomas N. Scortia (1972). © 1967.
• Atwood, Margaret. The Handmaid's Tale. Forced prostitution by the handmaids; and houses of ill-repute secretly provided for the bigwigs.

• Bujold, Lois McMaster. Vorkosigan books. LPSTs on Beta Colony (Licensed Practical Sexual Therapists)

• Carey, Jacqueline. Kushiel's Dart (2001) & sequels
• Carr, Jayge. Leviathan's Deep (1979). Not a major theme, but there are definitely whores -- they're male. The society isn't primarily capitalist, so it may be that they are fulfilling religious service more than for money.

• Kwasny, Melissa. Modern Daughters and the Outlaw West (Spinsters Book, San Francisco, 1990). A small Wyoming town is infested with quirky lesbians, ghosts, and politics. One of the ghosts -- a leading town-mother -- was the town madame / hooker.

• Lackey, Mercedes. One of the Gryphon books have a sex-worker as a protagonist; these particular sex-workers are respected in society, and are combination therapist / sex therapist / masseur, and are of both sexes. Examples of that profession crop up in other of her later Valdemar works.

• McMahon, Donna. Dance of Knives (2002) (major character was previously a sex worker; sex workers are common in the society)

• Oberndorf, Charles. Sheltered Lives (1992). After the spread of "hives," a deadly STD, the government sets up shop with licensed sexual service workers.
• O'Driscoll, Mike. "The Future of Birds". Transsexual Latina MTFs are all the rage in the future.

• Schulman. Rainbow Cadenza. All women are required to spend several years in "the Service" - prostitution.

• Waters, Sarah. Tipping the Velvet (It's not fantasy/sf, but readers of fantasy might well like it; the London of the early 20th century is pratically fantastic. This is a lesbian picaresque novel & well worth reading.)
• Whedon, Joss. "Firefly" (character of Inara is a Companion, a registered multi-talented professional who at least sometimes includes sex in her services; she is regularly described as a whore by major character Mal; in episode "Heart of Gold", a former Companion is now a madame of a house of prostitution)
• White, Ted. "Welcome to the Machine." Amazing, June 1976. [bisexual male prostitute in the future]
• Wolfe, Gene. Free Live Free