My first recommendation would be to try Lavalife's Intimate Encounters section; you sign up with them and then decide which of the three sections you want to be a part of (Dating, Relationships or Intimate Encounters).
You can use different handles in each section under the same account too, so no one will be any wiser if you want to advertise for one thing in one place without ruining your chances for something more should it come up.
Good sites can go bad, and those I don't recommend may improve.
Of course, new sites will debut that may or may not be of merit.
We can all help keep each other safe by reporting dating scams.