Larry Saboto has had a stellar prediction record over the 5 elections in which he has used his "Crystal Ball" blog to prognosticate.  His 98% success rate in 2010 is reason enough to give some weight to his final outlook for 2014.

In a nutshell, Sabato sees a GOP gain of 8 seats in the Senate and 9 in the House.  Republicans would lose a net 3 governorships in his election scenario.

Sabato never claims perfection and sees the election prediction business as a fun way to inform and educate the public:

As is our longstanding tradition, we at the Crystal Ball attempt to call every election for House, Senate, governor, and in presidential years, the Electoral College. After studying these campaigns for months or years, we believe we owe you our best judgment about the outcomes. While we’re proud of our overall record over the years, we always miss a few calls, sometimes more than a few. Toss-ups are vexing, and the massive amounts of intelligence from polls, analysts, campaign managers, and party officials can be exceptionally contradictory. Not many of our sources have ever attempted to mislead us; they sincerely believe this candidate or that one will win — and smart people on the other side of the aisle are equally convinced their nominees will triumph.

The day after any election (or runoff or recount), when the actual winners are known, it all seems so obvious in retrospect. But of course it isn’t, pre-election. We apologize in advance — and we’ll do it again post-election — for all the races we will inevitably miscall. Our goal is perfection, and we’ll achieve it on the proverbial twelfth of never.

We also want to take this opportunity to thank all of you who have bothered to take our calls, or to e-mail us or tweet to us about your take on the 2014 contests. There are thousands of clever, canny observers and activists out there of all persuasions and ages, and we’ve learned much from you. Please continue to share your knowledge and views with the Crystal Ball team. We can’t always find the time to respond personally, but we read every missive you send us.

Finally, let’s keep the enterprise of election prediction in perspective. We’re not exactly curing cancer. This is fun for us and, we hope, entertaining for you. But the serious purpose, other than trying to understand why voters behave as they do, is engagement and civic education. Everyone criticizes horserace coverage, but the truth is that millions are fascinated by the discussion of who’s ahead, who’s behind, and who’s gaining. Often it is that particular aspect of politics that serves as a hook to reel in citizens and open to them the consequential world of elections. Once they are attracted by “the only sport for adults,” as politics has been termed, many people are more inclined to learn about the candidates and the issues, and to participate in the process more fully.

An interesting note: Sabato updated three Senate races that he moved from the "toss up" column to "leans Republican."  All three races moved toward the GOP:

The Kansas race between embattled, weak Sen. Pat Roberts (R) and independent Greg Orman is perhaps the closest, most difficult-to-predict Senate race in the country. However, at the end of the day, a Republican has not lost a Senate race in this state since 1932. It may happen, but we just can’t pull the trigger and predict it. LEANS REPUBLICAN

We’ve been calling Georgia and Louisiana “Toss-up/Leans Runoff” in recent weeks because we expected both to eventually go to runoffs. Louisiana will, and Georgia might, but we now believe Republicans are favored to eventually win both. So we’re just going to call both LEANS REPUBLICAN going into Election Day: If both do in fact go to runoffs, then the Leans GOP ratings will apply, at least initially, to the overtime contests.

If Sabato is right, we will probably wake up Wednesday morning to a Republican majority in the Senate.