Not nearly as 'exotic' as some of these suggestions, but how about the Scottish Highlands (and Islands if you want to expand it a bit)? Some fantastic walking that can be made as difficult as you like, you can take a tent and camp, so cheap lodging, and walk from point-to-point over a few days, carrying everything you need with you (please take the normal safety precautions of doing such a venture of course) and you should certainly be able to get a long way there on miles. I think some of the scenery is absolutely breathtaking, and certainly standing in some spots, without another soul for miles around, you really feel as tho you are the only person who has ever set eyes on the valley you are looking at. I think your wife should be fairly comfortable with the country choice too.