We know and really like the fact that the RS books assume you're ready to walk, move and be a part of the new place you're going to - its part of what we like about Rick's philosophy. That being said on this most recent trip with my mother (73), my aunt (76) and uncle (78?) we were struck by how few details were given as to the terrain we had to cover. My mother, who is in good shape and generally walks about 4 miles a day, pulled her thigh muscle walking up a pretty steep hill at the Folk Museum in Oslo - that slowed her down the remainder of the trip (and she did it on the first day!). Both my aunt and uncle, who are hikers in the White Mountains of New Hampshire, felt the "hills" and walks were not clearly described.
The the Grieg House in Bergen we were under the impression that there would be an easy bit of terrain - and it is if you're not walking with a limp - but the public bus drops you off at the bottom of a steep, longer hill and the tourist info bus drops you off a reasonably flat, shorter walk at the top of the hill but we found the description in the book to be misleading.
It might be helpful if more descriptions could be added as your readers are beginning to age; the younger crowd will be able to use them as landmarks. "Steep hill", "long uphill/downhill walk," "many steps/stairs" would be helpful. We don't plan to stop traveling but we will need to be more mindful of these issues when working on the next trip.