A couple suggestions - Alan Hollinghurst (particularly "The Swimming Pool Library") and Christopher Heim ("Hold Tight" especially). David Leavitt and Edmund White may not do quite as much sex in their novels, but they're decent choices. If you like your fiction a little grandiose and wordy, there's Harold Brodkey (I found him kind of insufferable, but I was a horny teenager looking for the sex scenes…). Also, the Australian author Christos Tsiolkas writes some moving and sexy fiction.