How about 12 year term limits for congress and senate? After that they have to wait for a period of time (e.g., 4 years) before running again. Just a thought....
To me term limits are less of an issue if there is more accountability via shorter terms; if someone can win ten consecutive elections every three years, then I believe they must be representing their constituents well.
You have to amend the constitution to enact term limits. It was passed by the Gingrich congress, signed into law by Bill Clinton, and knocked down by the SCOTUS.
My proposal is to end and an all post-office benefits for elected officials, including esp. pensions. Let them have an unmatched 401K plan nothing more. I think that would serve well as defacto term limits and no amendment required.