If you have a lot of traffic in/out of a DL hub market (and MCO is enough of one) or your company is based in a DL hub, DL will most likely NOT give you a corporate agreement.

However, if you get an agreement with CO or NW, you can still take DL flights and earn miles on CO or NW. Try for a status match.

I have found US to be a high-price leader in many markets.... might want to shop the rates and see who offers lower rates in the markets you frequently fly to.

If you're non-status and can't get/maintain status with any one or more carriers, I've reached the conclusion that WN is seriously worth considering.