I think some weirdly basic concepts should also be applied, to make elections "matter" less.
1> The leaders of the House and Senate should have absolutely zero control over whether/when bills are submitted to their respective sections of Congress. What Mitch McConnell has been doing should literally not be possible, not without criminal charges being filed against Mitch at least. The House submits a bill to the Senate, it goes to a vote after a set period of time to allow Senators to read it and come to a decision
2> No Presidential immunity to criminal charges. Being charged (not convicted, just charged) means immediate removal from office. VP steps in as President. If this causes problems because so many officials are committing crimes, your country's already broken and it isn't this policy that's the issue. And before you say "That's crazy and impossible!", this is literally how it works here in Canada.
3> Ethics watchdogs, with teeth. Independent agencies whose role is to ensure ethical conduct by elected officials. Lying to constituents or misuse of funds and such means penalties up to and including removal from office, from any level even up to and including the President, and potential criminal charges (they'd hand that information off to the DoJ in that case).