The interactive maps on ReidsEngland.com
For every destination, there are actually two ways to peruse all the sights, hotels, restaurants, activities, pubs, and useful planning and practical points of interest (tourist offices, train stations, etc.).
You can, of course, click through the various thematic sections, much like a traditional print guidebook. Or—if you are more visually minded—you can select the Interactive Map and see the locations of all those points of interest at once. (This is also quite handy for finding, say, a lunch spot near a sight, or learn what's close to your hotel.)
Just click on the "Interactive map" image on the destination's homepage (right above the "Useful links") and you will get the full-sized map. (Yes, I know the map image is always taken from London, but that's just a placeholder; a click will take you to the appropriate map for whatever city you are in.)
It might take a few seconds for the page to load (plotting all those points of interest takes a while), but have patience!