Imagine the difference the place would look like if the STATE congresses elected the Federal senators to REPRESENT THE STATE INTERESTS on the fed level. Suddenly state politics would be super important again and the people in DC would be more answerable to state differences and not be essentially super-congressmen with 6 year terms.
Of course, we'd have to repeal an amendment.
I've also argued in the past to remove as much of the entitlement programs from federal control and send it to the states for two reasons: a) it would make state politics that much more important, meaning more incentive for locals to be involved in democracy and b) it would allow the people greater access to changes, experimentation, reform, etc.
So for example, if the federal income tax didn't cover SS, Medicare, medicaid, public schools, etc. but only defense, the FDA, CDC, and those types of things, we the people locally could decide if something was too expensive for our state to fund.