hotly debated and often discussed! LOL! There are piles of threads that may cover specifics....here's a link. My own personal experience...I can't give you a dollar amount because I am doing all the labor myself. It cost more for the exterior doors and windows (the casing is wider and is usually a special order). Lumber is a bit more, insulation is more (but you also have better insulation). I love the nice wide window sills I get with the thicker walls. No doubt it is stronger. Your buuilder should be able to give you the upcharge amount for using 2x6 prior to writing the contract.

Here is a link that might be useful: 2x6 search

Thank you muchly! Greatly appreciated.

I don't know much about $$$$ just wanted to throw an option out there. We used a mixture of both. 2x6 on outside walls and 2x4 in most interior.

'I don't know much about $$$$ just wanted to throw an option out there. We used a mixture of both. 2x6 on outside walls and 2x4 in most interior."

Oooooooo! Good idea! Thank you.

We are doing the same as charliedawg. 2x6 on the outside and 2x4 on most inside walls. Some interior walls needed to be 2x6 for plumbing purposes. I need 2x6 to meet my R21 wall insulation code anyhow.

Great info on those archived threads! (And not all of it's mine.)

Here in Toronto, custom builders switched to 2"x6" many years ago. Still, I see lots of lower-end projects using 2"x4" with exterior insulation to meet Code. For a single home, I don't think the savings are worth the hassle of twisty lumber and the added detailing to ensure exterior insulation is properly installed. In the interior, so many of the 2"x4" walls have to be strapped to clear heat ducts that I go with 2"x6" in the first place unless space is at a premium.

I also intend to use 2x6's on all exterior walls after reading what the Wise Ones have told me on this forum. A local building supplier told me he had calculated a $1300 framing cost difference on a house with 3600 sq. ft. living area. He also advised that I should allow an additional $40 per window and door.
I'm not sure this cost difference would be applicable to your locale. The cost of building materials in our area have not gone down as they have in some other areas.