You absolutely must go to Bath! Lots of Austen-themed things, plus you can "take the waters" at the Pump Room. Bath features prominently in "Persuasion" and "Northanger Abbey," and seeing the real place is very cool (despite the fact that Austen herself disliked it, to my knowledge). Also neat to see is Winchester, which is where Austen's death-place is. The cathedral (particularly the roof tour) and the Winchester Bible are big draws, also.