I think I'd suggest a more generous Senate term limit. Three terms (18 years) would allow for someone to see out a complete Presidential super-cycle, for example.
The word Senate is etymologically related to "senior", it's a place where you _want_ people to be able to develop a lot of institutional experience.
edit: I see the "term limits are anti-democratic" takes elsewhere in the comments, so I guess let me narrow the above ask to "someone who isn't opposed to term limits, but thinks this idea is flawed."
Put the electables in isolation cells fromwhere they one by one end up on the Tee Vee, give voters an app with AYE, NEY and Uhh? The questions are red by the winning HR lady but also appear on the app.
The applicant writes the fizzbuzz etc etc
Then, after the job interview, we give the job to the most satisfying candidate!
It's not necessary but I would also add a series of certificates and diplomas for the voter to show they actually have some kind of idea what the job involves. The level 1 certificate should be supper simple and easy to create. It will grant you 0.1 extra vote power. There could be as many levels as we want but to grow beyond [say] 50 votes should require a mythical effort impossible to attain for 99% while we aim to reserve the right to cast 5000 votes for 1 to 5 people with supper human abilities.
The top 20 should have to explain their AYE's and their NAY's to the Tee Vee audience.
I’m not disagreeing with the rest of your comment, but I’m going to challenge the notion that this etymological connection carries meaning. The word comes from Roman Senate, and in that context in Latin “senior” really meant people with higher status rather than age. Latin is full of these weird double meanings. Compare to seigneur in French or señor in Spanish. Also, the House of Lords in the United Kingdom.
All those using it to mean 'factually' are out there making a farce of the language. A farce!
The result is that you can stay as long as people keep voting you back in, but you lose the incumbency advantage and end up with a higher turnover rate without ending up with a 100% turnover rate. And you make them learn how other parts of the government work. It wouldn't hurt a bit to see long-term members of Congress do a two-year stint in an administrative agency once in a while.