I was thinking about your situation more last night... so here are more of my opinions...
(this is all the way it is at my airline, at least, so pardon me if I am off base here)
If you go to NWA as an instructor, you are considered management, right? As a management pilot you get your type and then can also fly the line as required to maintain manning and your own currency/experience. You will also get to operate the simulator, I imagine. All of this is far better than logging SIC time full time at a regional and will make you so much more hirable than Joe Schmoe at Regional X. Plus, your QOL will likely be WAAAAAAAAAAAY better than going to a regional, but maybe that isn't an issue with you.
If you go to a regional, you will not have any advantage over anyone else as far as getting to a major goes. You will rack up total time, yes, but although you have the required PIC time to apply to a major, several years will have passed since you logged it. This won't go unnoticed.
If full time reserves is what you want, there are plenty of billets but in various locations. Can you pick up and go to the place where the opportunities exist? If not, I would add commuting to a regional job as a huge detriment and another stike. You will never be home or see your family.
I am not all doom and gloom as I guess this email makes it seem, but I would hate for you to go to a regional thinking you are going to knock on Fed Ex's door in "a year or two." Not likely.
And why don't you apply right now to the big three? You TT isn't that high, but I have heard of stranger things as far as hiring goes.