No question, all politicians in any position should be subjected to term limits. The limits for different positions can be negotiable, but no one should be allowed to serve infinite terms. The result of career politics is that nothing at the upper levels of government is actually "Representative" of the people; the U.S. is a representative constitutional republic, not a democracy, and so the work of the government is intended to represent the will of the people. Instead, career politicians make almost all of their decisions based on their own careers, on the wishes of special interest groups, and in exchange for favors from other departments. Term limits would force politicians to make the most important changes during their time in office, and then to make way for new voices.

By the way, I consider the "expert politicians" argument invalid; anyone who wishes to remain in politics after limiting out can serve as advisers or run for higher or lower office.

Term limits seem like a good idea to combat the development of professional politicians at the national level. 

Maybe one way to meet the challenge of legislative complexity/necessary lack of expertise pointed out in the second post is to extend the term length while keeping the term limit to a single term. 

The problem is that the concept of “expert members” really translates to being an expert politician.  The vast majority of the members of congress come from legal backgrounds, with a smattering of business based experience.  Where are the scientists, the engineers, the educators, or industry experts?  Basically, you have an institution that is filled with people who are experts at campaigning for reelection and working within the system as it currently exists to make sure that things within the system change as little as possible. 

The problem is that the most powerful committees are full of people who have “seniority” and not the people who have the most relevant experience.  If you don’t have a limit on how long someone can serve in a particular position, then age or experience become the default when it comes time to choose people for specialized positions.  The respective presidential nominees are a great example of this concept in action.  In most cases, things devolve into a simple “it’s my turn now” decision making process within each party.

Look at the current Committee on Space, Science, and Technology for example.  Lamar Smith is someone who admitted that he abandoned a career in science after taking a freshman science class and instead choose to pursue a career in law before becoming a life-long politician.  Nothing against Smith personally, but wouldn’t the country be better served by literally any scientist in the country serving in that position, as opposed to someone who has done nothing but politics and law for the last few decades?

There are many points on each side of this argument. 

The most important point on the pro-term limits side is that term limits would make Congress be more in touch with the American people.  This argument holds that rotation in office would ensure that we would not have a bunch of career politicians who have forgotten the real world and who care only about getting reelected.

The most important point against term limits is that it would rob Congress of expert members.  The issues that face Congress tend to be very complex.  Members who only serve a short while will never master those issues.  Congress would be left without elected members who were expert in various areas.  This would give more power to unelected staff and to lobbyists.