The Polks may be you best bet. But also consider the Boston Acoustics CS260 II's. I helped put together a very nice budget system for a friend with the BA CS26 bookshelfs. I have always liked the sound of these bookshelf's as they have a slightly warmer rich and smooth sound. Their midrange is excellent and the tweeters are laid back. They perform way above their price range. Here is a review on the towers.

Boston Acoustics CS 260 II Review | Digital Trends


Too bad you are set on Towers, there are more options and better sound to be had with Bookshelf's.