Marathon season will be back again before you know it. From spectacular scenery to epic post-race parties, Active.com have done the research so you don't have to. Here is the completed guide: http://www.active.com/running/articles/2017-fall-and-winter-marathon-guide.
You can also just select the region you'd like to run in below and find the ideal 26.2 for you.
West Coast Marathons
Marathons in the South
Marathons in the Northeast
Marathons in the Midwest
You can find more marathon races here: http://www.active.com/running/marathon.