A lot of those are very commercial and a bit shabby, full of seaside casino / spa offerings. But a few countries do a notably good job. In the process of cleaning out my stack of accumulated brochures, I came across one from Korea. With a brochure like theirs, you wouldn't even need a guidebook. It lays out suggested itineraries for neighborhoods in Seoul (and for entire other cities), describes regional foods, and has what look to be highly usable maps. I suspect they are taking lessons from the Japanese, who have great walking tour maps in major cities and who have some of the most helpful tourist office staff workers in the world.
Korea doesn't seem to be high on the tourism agenda for most Americans, but this brochure should help.