You know, I could go for term limits for both Senators and Representatives. Give them both the same thing as the military, you can retire after 20 years of service, but are forced out at 30 with retirement benefits. Why do I say this? Because after being in office 20 to 30 years, a person can become locked into their thinking and won't be willing to accept new ideas from the younger crowd. Saw it in the form of CPO's who were unwilling to accept changes to the Navy when they happened, even though some of the changes were good ones. In the military you are eligible to retire at 20, but mandatory retirement (unless you have a critical specialty), is at 30 years of service.
And, considering that the age you can become a Senator or Representative is 35, with 30 years of service, that would put them at mandatory retirement at 65 (if they were elected young), which is a good age to put a representative out to pasture. Most would end up retiring at 70 to 80 years of age.