2010
AZ: Flake - Much more breathing room for on the job training and AZ Class III 2016 may be trouble with McCain
CA: Campbell
CO: Norton
CT: Simmons
DE: Castle
NV: Porter or Lowden/Tark within the primary
Probably only gets you the big three blown seats, but the others may have been closer.
2012:
AZ: Shadegg, possibly Cardon within the primary
FL: Hasner - I was wrong, sue me!
IN: Skillman or Rodkita. Preferably Pence, but he ran for Governor.
MI: Lynn-Land
MO: Talent, Steelman or Brunner within the primary.
NE: Bruning, but Fischer isn't a problem unless the stories of it being close are true.
ND: Wayne Stenejhem, losing his brother may have made him drop out though.
OH: One of the Steves.
LaTourette or even Austria.
VA: Bob McDonnell
WI: Hovde (a determined guy with a ton of money flooding the markets on day 1 after the primary, like Smith in PA. It is why Cardon may have been better than Flake in AZ, as well.)
AZ and IN would be off the table, ND, NE, and MO locked up as gains from the Dems. VA would be tilt to lean GOP. FL, MT, WI, OH, PA and MI would all be competative.
A better run Romney for President campaign, and you have good chance of 55 or 56 Senate seats. Slim outside chance to run past that to 60 with better organization at the Pres level in ME and NM which would have aided Summers and Wilson.