MAPD
I'm a former MAPD instructor from ten years ago. I worked for John Greene. I second most of Eternal Optimist's comments about the place, and especially those about Mesa, the company.
A few additional caveats about MAPD. When I was there students did get "the interview" but really had to watch their Ps and Qs. In other words, no matter how stupid or inane things seemed, don't raise your voice or complain because it might torpedo your chance for "the interview." Of course, getting "the interview" was the students' prime motivation at MAPD.
Some students do not get "the interview." I had one such student. He was an AF veteran who suffered some sort of foot injury and got out on a disability. He felt he was owed. He was not owed.
Greene had posted a long piece of butcher paper on the wall which set forth deadlines for completing flights, lest students be hauled into his office for a reprimand. Students thus felt more under pressure to complete flights and, in my 2¢ opinion, less concerned about learning. As a more or less dedicated and conscientious flight instructor, that bothered me, as did other things about Mesa.
MAPD offers students a great opportunity, as Eternal Optimist said. But there are no guarantees. There's no guarantee that you'll be hired by Mesa, although the company pretty much knows who you are from MAPD. Eternal's husband clearly had the stuff Alaska Airlines wanted and his timing was good. But not everyone has such qualities, luck or timing. Mesa Airlines, and all that it implies, may be the only 121 stop for other MAPD grads. In other words, take off the rose colored glasses and view the place realistically.
Finally, you have to be 23 to be a Captain. You have to hold an ATP certificate to be a 121 captain, and 23 years of age is the minimum age to be eligible for an ATP.
14 CFR 61.153(a).
Good luck with your plans.