Yglesias ticks off a number of procedural reforms that would make political life in America better. I would add to this the idea that we really ought to look at making the House of Representatives much larger than it currently is. Representatives in the large body of most nations' legislative body tend to represent between 75,000 and 200,000 constituents. The US, there's one Congressman for every 700,000 constituents. Getting down to the international norm would require tripling the size of the House.
It should be noted that massively increasing the size of the House would have other interesting consequences. A district with 200,000 members would have a off-year primary electorate of about 15,000 to 20,000 voters. This is a small enough number that it's plausible for a candidate to meet, in person, everyone who's going to vote for them. Medium sized cities would have so many members that campaigns would be waged strictly by direct mail, or we would move to multi-member districts. Having more members would lead to more factions, which might make cross-partisan coalitions more common. Even if we don't go all the way to a 1,300 member House, there's no reason for body to have fewer members that British Parliament, considering Great Britain has a population one-fifth the size of the States'.