In races and long runs, I try to go as long as I can without music. This may or may not happen at Gansett for a number of reasons. It is a VERY small marathon. Probably 100-120 runners this year. That's small for any race, no less a marathon. Volunteering last year, I saw that there were some clusters of runners. Most ran alone, though. It is a two-loop course. Run 16 miles, then run 10 miles. Guess what? You pass all of the mile markers for the second loop in the first loop. I am familiar with most of the course, but that is not necessarily an advantage.
I started with my Shamrock Marathon playlist and edited it down. Any song that I did not like during Shamrock was cut. Goodbye, Elevation by U2. The location-specific songs that dealt with the ocean or water are also good for Gansett.
I didn't have time to add much, but I recently purchased (and still have $50+ in iTunes GCs):
Foo Fighters - Word Forward
Outasight - Tonight Is the Night
Calvin Harris - Feel So Close
David Guetta & Nicki Minaj - Turn Me On
Civil Twilight - Fire Escape (thanks, Pandora!)