Republicans are set to do very well tomorrow. But they could have done much better. Richard Viguerie makes some excellent points in his pre-election letter on Conservative HQ:

Republicans never win elections unless the elections are nationalized. 

GOP candidates and committees have spent hundreds of millions of dollars in the closing months of this campaign, but it has been spent almost entirely on individual races.

If 2% of that money had been spent on national TV summarizing the core issues in this election, many more state legislators, House, Senate, and Governor races would have been won by the GOP.