Having walked the Vezelay path last July / August I have a few little comments to add to those already presented. Firstly - yes there is a lot of road walking, but as a general rule it is along fairly quiet roads. However last year, due to the massive storm earlier on, the lovely walking through the pine forests of the Landes was somewhat marred, and indeed there was an agonizing 7 - 10 km stretch where pilgrims were forced to detour along a major road. I was astonished at how quickly the authorities had dealt with all the felled trees, but nontheless there was a substantial stretch yet to be done when I was there in late July / August. Perhaps by now this may have been cleared up. I don't have maps in front of me while I write, but from memory the least amount of road walking is from Vezelay to Bourges.
The other thing that astonished me was the number and quality of refuges along the way. Whilst there are also a number of people who take pilgrims in, due to the lack of refuges in that town or village, I was surprised at the wonderful supply of refuges too. They varied in price from Donativo (with a minimum charge of 5 Euro) to about 12 Euro. In a stretch where there were no refuges there were a number of delightful private Gites (approx cost - 15 - 18 Euros).
A word of warning though for the refuges. You will need to plan ahead prior to weekends as quite often the key is to be collected from the Marie - which closes early on Friday evening for the weekend! By making arrangements with the Marie though it is quite possible to collect a key, or be given the code for the door.
Some of these refuges are in very out of the way places and the local people stock cupboards with (canned and dried) food so that weary pilgrims can buy food from the "store" and have a substantial meal. There are a number of refuges where you even have the opportunity to sleep between sheets, what luxury! The refuges tend to be small, but very well equipped.
By the way, for anyone starting before Vezelay there are a number of refuges for pilgrims between Troyes and Vezelay, although they don't appear to be listed - or weren;'t when I was there. A visit to the tourist office leads one to them.
Hope this helps, Janet