I would be in favor of fairly expansive term limits to help mitigate the concerns but still encourage a little bit of turnover there. Something like 18 years for House and 18 years for Senate. Between the two, you would have the ability to have a 36 year career on the Hill which is more time than many people spend in one job.

That gives plenty of time for continuity and knowledge building but prevents any one person from setting up shop their entire life and preventing anyone from the next generation from having a chance due to the incumbency advantage.