Quick follow-up - here are a few to consider (some of which have
already been mentioned). I'm ordering them in terms of Distance from
the PNW (I'm in Seattle):
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Sky Sailing (Warner Springs, CA)
Williams Soaring (Williams or Montague, CA)
Arizona Soaring / Estrella Gliderport (Estrella, AZ)
Moriarty - Sundance? (Moriarty, NM)
Burt Compton (Marfa, TX)

Pretty much all of these have CFIGs and DPEs available to finish up
your rating and give you a checkride. Call around, check prices and
your travel costs, chat and see which outfits seem to jive with your
personality. And lastly: Study and prepare BEFORE you go. You're going
to have your hands full learning to handle their operations and their
gliders, so make sure you know the rules & regs stuff (as much as you
can) so you can concentrate on flying while you're there.

Good luck!

--Noel