Of the toss-up Senate races, the Republicans will win Alaska, Colorado, Iowa, Kansas and Louisiana. They might also win Georgia, but it will be very close. I believe the Democrats will win North Carolina and New Hampshire.
In the House, I believe the Republicans will pick up 12 seats.
Bonus prediction: Ted Cruz will not run for president in 2016, but rather focus his energy on forming a powerful conservative block within the Senate Republican majority and will drive the Senate agenda for the next two years. Stepping out of presidential politics will enable him to ally with Rand Paul and Marco Rubio, further strengthening his hand in the Senate. He will use his considerable brilliance, charm and organization to bolster Republican chances to retain the Senate in 2016, when they have a huge number of vulnerable seats to defend. If he succeeds in engineering Republican retaining control of the Senate in 2016, he will make a run to be Majority Leader and probably win.