ScottMC,
This will work for your scenario I believe.
The inclusion of a "command-s" call is NOT advised in 99% of cases (because it continues the routine), but for the exact scenario you describe, it will work if implemented this way.
(defun c:PRG ( / e)
(setq e (entlast))
(command-s "_.PLINE")
(if (not (equal e (entlast)))
(command "_.REGION" "l" "")
);if
(princ)
);defun
Best,
~DD