See page 13 of this month's Soaring mag. THere's an excellent
depiction of where we may fly without transponder or comms. Having
said that, it's always a good idea to chat with the controllers if
(your and their) workload permits.

I've gotten low near a towered airport such as Pueblo and the guy must
have been starved for company, as I got the full 20 questions as I
ground around in a weak thermal before finally getting away.

-Tom