Personally, I'm opposed to the scans.
I know many are saying it's a violation of constitutional rights, and I too think it is.
The counter argument that I gave consent and have other options? True, but, point is, the government has no reason to be doing this REGARDLESS of consent.
Let's put it this way, if there was a mass terrorist poisoning at grocery stores, say someone went into one in NYC and sprayed all the meat and produce with a poison and no one caught them, and the government next said all grocery stores had to have guards and protocols like airports for entry, would the same argument apply? Sure! You don't have a RIGHT to shop at a grocery store, you can always go to the source, or grow/raise your own food! You can go to co-ops or things like that!
How about if some terrorist blows themselves up in a walmart? You don't NEED to go to a walmart, so by going you're giving consent to that search!
Where do we stop? At what point DOES it become a violation of our rights? Yes consent is 'given' but, at the same time as many people do have a NECESSITY to fly. Is it really proper for the government to say "You HAVE to give us permission to search you, or you can't use a PRIVATE industry!"
There are a LOT of ways a major terrorist attack can occur, forcing consent to a search or denying the use of a private industry, whether technically constitutional or not, I feel definitely goes against the SPIRIT of the constitution if nothing else.