Last year was my first ever rally...spectator only. There are really only 2 stretches of road where the stages take place (that can be viewed by spectators). Each stretch of road is raced in one direction for one stage, then in the opposite direction for the next stage. My friend and I watched the last 3 stages...2 in the afternoon, and 1 at night. The two later afternoon stages were along the Iron Bridge course. For one of these stages we stood near the bridge, which gave an exciting vantage point as the cars careened across the bridge and around the tight corner. We were late arriving for the night stage (take a flashlight!), and stood on a ridge in the woods amongst dozens of other fans.
Hints:
Arrive early if you want to get a good spot to view the stage
The race marshals frown upon spectators going outside of the designated areas (I know from experience. My friend and I saw some people standing in a good viewing spot. The people left, but we stayed...that is, until the marshal told us to move.)
Dress warm
Bring maps with you printed from the ROTP website to help you find the stages
Bancroft will be VERY busy on the day of the rally - my friend and I had supper in Wilberforce
These pics were taken from the Iron Bridge, and from the spot that was out of the spectator area.