Another thing I would do is listen to noaa weather periodically.  They will tell you if ducting is present.  When I was living in d.c., stations in Wakefield and Charlottesville Virginia would alert me that ducting is present.  Last fall, I experienced a phenomenon where I was able to receive fm broadcasts from Iowa, Minnesota and Wisconsin.  This is from my high qth in western Maryland.  Also on Father's day in 2006, I was able to hear stations in Florida on the fm band for a very short time.