We went this same week in 2013 and are going again this January that same week. The crowds were pretty low and we did not see any increase in crowds in the parks due to marathon. The hotel was more crowded over the marathon weekend, beginning on thursday and so were some of the restaurants but not the parks. We had short waits for almost everything. Temps can vary a lot but in 2013 it was HOT, in the 80s. In 2011 it was in the 50s one day and 70s the next.