Trisk, here is the link to the tour we are doing. I noticed it's rated as "easy going to moderate," but we got the specific details a couple of weeks ago, and I would not consider it easy going! There are a few big climbs, which of course, I guess you could skip, to make it easy.
Emily's experience and comments mirror mine exactly. If I remember, Trisk, you were close to my height, so anything bigger than a 26er would not be my choice.
Sometimes I get the yen to buy another mountain bike, to do the kind of riding Emily describes. There just aren't a lot of dirt roads right around here, although, I seemed to have found some on my birthday "ride 60 for 60" ride last year, in Wayland, MA. Not fun on my road bike, but, I did it.

http://www.cyclingcountry.com/CycleT...cling_Tour.htm