I have done the Fletcher Flyer several years - it was my first century - and is an awesome ride as a first century - well supported - well marked and as others have said FLAT - some rolling "hills" - nothing but what we call small rollers around here. I routinely ride on parts of it for training. It is the most tame century I have ever ridden.
It can be hot or cool - although wind is rarely a problem around here. It is a large ride with bunched starts - starts in three waves depending on your average speed you are intending to ride. I would make sure you are comfortable riding in a group and in a paceline - as the ride is very bunched up at the start.
Hope that helps.
debi
"Character cannot be developed in ease and quiet - only through experience of trial and suffering can the soul be strengthened, ambition inspired and success achieved" - Helen Keller