I want to plan a trip to Ireland, Scotland, and England. What should I visit, and where should I stay?

Brittany B asked: I'm planning a trip to the UK and Ireland (not this summer, but the following) and need some help planning my itinerary. I would like to visit Dublin and County Cork, Edinburgh, the Highlands, London, and Cornwall. What other places should I visit? Any suggestions for hotels, inns, BB's? I would like [...]