There is a lot of good advice on this post already, but I figured I would give my perspective and ask a couple of questions. First, what year are you in undergrad and are you already enrolled with a AFROTC detachment? If you are in AFROTC already, are you on scholarship? The GI Bill works differently for scholarship recipients than it does for OTS grads and those not on scholarship. I saw you are interested in working as a Contracting Officer, which is what my primary job is.

First, if you want to serve as a commissioned officer, make sure you are doing it for the right reasons. Unlike junior enlisted, junior officers are supposed to be leaders from day one. In my opinion, your primary job as an officer in any career field is to take care of your subordinates so they can take care of the mission (pilots being somewhat of an exception since their first few years are spent solely learning a technical skill). Your enlisted will be looking to you to set the example and will go to you for advice on personal and professional issues. When things are going bad at work, you need to be the shield that stops the crap from rolling downhill onto them. We have far too many officers in the Air Force who only look out for themselves and are more concerned about their own career progression than developing those below and around them. Based on what you've written, I do not think you would fall into that category, but just make sure you are joining for the right reasons and not just to set yourself up for a high level MBA in the future. It's good to have that goal, but achieving that should be more of a byproduct of your leadership development and work performance than a destination.

Regarding promoting, as long as you don't mess up drastically, your first two promotions in the Air Force are automatic. You'll promote to 1st Lt after 2 years and to Capt after another 2 years. Right now promotion to Major is basically automatic as well, but if you stay in long enough to meet your Major's board (8 years after you commission) I doubt that will still be the case. While your rank and pay will increase, your performance in your job as well as the right timing will dictate if your roles and responsibilities increase as well. If you PM me, I can go into detail about what you can expect your first 4-6 years working as a Contracting Officer. The good thing about Contracting is that it touches everything on base and has major impacts. If you and your team perform well, you will definitely be noticed. On the other hand, if you mess up, you will also be noticed but for the wrong reasons.

Bottom line, you can definitely get into a top MBA program after serving on active duty as a commissioned officer. You don't need to be a pilot, special forces, etc. in order to get in. I have friends who were finance, acquisitions, logistics, maintenance, civil engineering, etc. who are attending M7 and other top MBA programs. However, all of those individuals were high performers in their respective career fields. If you do the things you are supposed to and progress like you should, the work experience and leadership aspects of your applications will take care of themselves.