If term limits are appropriate for the presidency (they are), then they are good for all federal offices. Two terms max for any office.
Keep in mind that it was not until the second half of the 20th century that presidential term limits were added to the Constitution. Our founders did not write it that way and all presidents subsequent to Washington merely honored the standard he had set. IMHO, term limits are one of those Catch-22's that doesn't resolve itself so easily. If we a had a responsible electorate, educated in how our government was supposed to operate, that would be all the term limitation we would need. By that same token, in a free country, people should be permitted to vote for the person they felt best represented them and the needs of their district. Finally, if honorable people were seeking public office, they would step down before their "career" in politics became an issue.
Nobody loathes political careerists more than I, and I certainly understand the frustration with seeing all the insiders continuously returned to office for life, but keep in mind that term limits cut both ways. If you have a representative or senator that is kicking butt and taking names, don't be disappointed when some non-starter takes his place because the good guy can't run again.
Rather than term limits, I think there are two things that need to be done to revitalize our body politic:
1. Repeal the 17th Amendment. Restore the concept of federalism by giving the states their direct seats in Washington.
2. Separation of Powers: Practicing lawyers are by definition officers of the court, and consequently, members of the judicial branch. Their participation in the legislature is a conflict of interest. Barristers should have to be out of the active practice of law for a set period of time (i.e. 5 years) before becoming eligible for legislative or executive office.
Implement the above two, and I don't think there would be any more need for term limits.