Re your wife and the size of bike. We have just had a tour group of Americans through, and one of the ladies rode herself. She was 5’3″ and 110lbs, and we lowered one of our low seat, low frame BMW F650GS 800cc twins for her – this gave a seat height of 26″ and she found it very comfortable and quite manageable. The ride position is “sit up and beg”, for want of a better term. We will always have bikes in our fleet to ensure we have catered for everyone. Additionally, larger bikes like BMW’s R1200GS can be fitted with a low seat, so that even those with Duck’s Disease, like me (5’6″) can easily get both feet firmly planted on the ground.