Portland is spaced between Mariners and Giants/A's lands.
Charlotte is a shot below the Nationals/Orioles and maybe begrudgingly annexed for Braves loyalties. What should be emphasized for Braves Country is that it's a monopoly of the South. And that just seems unAmerican. Even the Yankees have to see the Mets in their existence.
As an alternative to the painful parameters of expansion (for things like franchise encroachment/television rights and more business realities like population with robust economy for consideration) I, like many, have talked about relocation. Because of the proximity of stadium struggling franchises like the Athletics and Rays, I say geographically, there are your moves. I think I've even done better than that.
I have proposed markets expanding locations, thereby adding more Major League cities into the mix, as well as expanding their team territory altogether (in which I've called a powerbrand). Portland plus Las Vegas for one team sharing those cities would be closer to be a powerbrand like the Yankees in terms of nation and number$. If you called such a team the West Coast Athletics playing in places like Oakland, Sacramento, San Jose, Portland, Las Vegas,...and even with some stretched justifications of the imagination like Salt Lake City or Boise, your brand is used by incorporating things named "West" like even Albuquerque, which is in another state with any big league brand in any sport. Also imagine Charlotte sharing the Rays with places like Nashville, Louisville or New Orleans. Brand it something "Eastland" and cities like Indianapolis or Columbus enter the talk of part time possibility. I'm not proposing that we go that far at this time but imagine this much.
Imagine the Rays and A's partially relocate (co-locate) in Charlotte and Las Vegas, respectively. And two more teams come into the league, expanding it for a total of 32 teams and 4 or more major league cities of baseball, all told. I'd even like to see Nashville and Charlotte share with Tampa becoming part of the born again Florida Marlins butt-hurt seat franchise where absence could possibly make the heart grow fonder for the tag team cities of east and west coast Florida.
It could be the West Coast Athletics and the East Coast Rays. A Montreal-Vancouver team could enter the league, and it could be rationed into any division that pleases the league and its logistics, even a central division justified as an average (in-between) where they locate. Let's call them the North Country Lumberjacks. That could even be a Portland shared brand of a triple team with West Coast being a Sacramento-Las Vegas A's in existence.
And the 32nd team could easily be a market encroaching the Rangers and Stros' "turf". It would be a team for the stretches of San Antonio and Austin in central Texas hill country. Think maybe "Banditos" baseball
See much more actual expansion, co-location and relocation talk for football, baseball, basketball, hockey and soccer on my blog http://prosportsexpansion.blogspot.com