The case of Sen. Stevens of Alaska is a warning about what happens when public officials serve for extremely long periods. I firmly believe that treating service in the House and/or Senate as a career creates greater problems than benefits. We end up with the likes of Sen. Stevens. Others that come to mind, and I am not implying they are criminals, are Sen. Byrd, Sen. Thurmond and Sen. Helms. These men become ingrained in the culture of power and in the end just hang on to hang on.
I think it is a mistake to provide pensions to legislators. Provide them a reasonable salary, make them participate in social security and encourage them to have a life outside of the Washington power circles. Over time they become so accustomed to power that they think they deserve things that they truly don't. Additionally, they lose context for the laws that they are tasked with enacting. Living inside DC is not anything at all like living in Peoria, Portland, LA, San Antonio or, really, anywhere else in the country.
It is deplorable that Sen. Stevens abused his position, but it is a danger to anyone that sits in a position of power for such a long time.