They might be the years you think they are, but probably not for the reasons you expect. Take your well-earned break from the next election cycle (EDIT: I was unclear. Meaning through the end of 2012, enough time for holiday revelry) but keep the following in mind.
Right now we have a struggle for the soul of the country. Despite winning a majority of votes cast for House seats in 2012, the Democrats will still be the minority party in the House of Representatives in the upcoming session of Congress. How did this happen? The short answer is gerrymandering, a term coined for Governor Gerry of Massachusetts, who redrew district maps in the state to maintain a sizable political advantage for the state Democratic party. It wasn't unknown before then, though:
Before the term "gerrymander" was coined and even prior to the U.S. Constitution taking effect, redistricting was already being employed for political gain. Late in 1788, just after Virginia voted to ratify the Constitution and join the union, former Governor Patrick Henry persuaded the state legislature to remake the 5th Congressional District, forcing Henry’s political enemy James Madison to run against the formidable James Monroe.
The reason we have so many gerrymandered seats right now is a large number of GOP-run statehouses. The Census bureau
has the data. In 2001, the GOP controlled 18 legislatures; in 2011, they controlled 26. They've taken pains to redraw the lines very carefully, quite possibly with outside assistance. In the 2012 election, some states where Democrats got elected to the Senate will have majority Republican House delegations.
So, the more distant year you should pay attention to is the 2020 election, but you should pay at least as much attention to the state level as you will the Presidential horse-race between, say, Donald Trump versus Elizabeth Warren, much though I'll have lots of popcorn ready for that race. The slate of statehouse legislators elected that year will determine how Congressional districts get redrawn (as well as state-level legislative districts) in all states that do not have non-partisan boards. This is where the Koch Brothers, ALEC, Sheldon Adelson and more will be spending at least half of their money. Of course, as long as the GOP can block attempts to tax their super-wealthy donors, or to let working people's labor be valued as much as investors' capital, they'll have plenty to spend. If you want to make it more fair, though, put more pressure on your statehouses. Texas did an off-cycle redistricting that led two other states to do similarly, all with partisan agendas in mind. If statehouses can be pressured to put non-partisan election boards in place with the power to draw fair maps, that cannot be called gerrymandering.
Closer to now, though, you should pay attention to 2016, and not just because it will have Marco Rubio versus Deval Patrick, or even more amusingly the Comedy Central Election of Stewart versus Colbert. I tell you, my popcorn popper will break three times that week. No, the race to watch in 2016 will be for control of the Senate.
In 2010 the GOP scored a large number of Senate seats. Not including Scott Brown (R-MA), who won the seat previously held by Edward Kennedy, they went from 41 to 47 total seats. Right now it's the only Republican-majority class in the Senate, with 22 GOP officeholders. If the GOP manages to keep the fires burning in 2016, they can keep enough of a minority in the Senate to cause major headaches. And they will, if the most recent three sessions of Congress are any indication. However, if they manage to lose enough seats in 2016 to hand majority of the seats over to the Democrats, then the GOP could conceivably be unable to filibuster--not that the filibuster is going to remain their weapon of choice if Harry Reid tweaks it back to an older method requiring actual talking and grandstanding. It's easy for Republicans to say the Senate is dysfunctional and stay mum on why when they can quietly hamstring it; it's harder for the GOP to say it's dysfunctional and avoid mentioning why when they're the ones the one singing loudly and knocking over wineglasses.
I'm not saying you should ignore 2014. The Democrats could lose like crazy if the GOP unleashes its usual lies-and-lucre tornado and people are caught sleeping. However, if the Democratic Party can at least keep that year neutral, or no worse than slightly negative, 2016 will be for the whole enchilada in the deliberative legislative body, specifically the one that can sign international treaties that can override domestic law via the Supremacy Clause. As Carlos Manuel Vazquez puts it in that article of the Harvard Law Review:
The Supremacy Clause gives treaties a domestic judicial sanction that they would otherwise lack. It makes treaties enforceable in the courts in the same circumstances as the other two categories of norms specified in the clause — federal statutes and the Constitution itself.
Gritty stuff.
Still, let me reiterate: we can take the rest of the year off from the next election cycle. I expect another right-wing cashectomy in the next two election cycles, but I'll worry about that after President Obama is sworn back in. It's not like the GOP can run on policy. "We kept taxes low for the rich, cut your unemployment benefits, fought against birth control and abortion rights and aid to single mothers, and we just ate your last piece of chocolate cake. Vote for us!" -- not a winning strategy.