First, just about every top school offers loan forgiveness programs for those who end up in nonprofit after b-school (usually the deal is you have to work for at least 2 or 3 years continuously post-MBA for the school to forgive the loan).
In your case, since you are a true non-traditional, I wouldn't completely rule out full-time programs. Even HBS or Stanford -- although you'd be a stretch, but still worth at least giving them a shot if you really want to go there. However, keep in mind that you will be the odd duck -- not just in terms of age but also professional background - that the biggest concern for adcoms (at any top b-school for their full-time programs) is not only your reasons for wanting an MBA right now, but your ability to fit into an environment where you will have very little in common with your classmates.
In any case, it's hard to really tell you what to do - you have an established career, you have more life experience than just about any full-time MBA student.
HBS as far as I know doesn't really offer an "executive MBA" - they offer specialized certificate type programs (more like month-long or weekend-long intensives) that are basically like taking a la carte courses. And yes, they are geared towards mid-career professionals like yourself.
Stanford Sloan is the only full-time executive program (others hold classes on weekends or weekdays with the assumption that you're still working) -- it may be another path to consider and probably a better fit for you than the full-time program.
It seems like you are really caught up with the "brand" thing - and I can't be bothered to convince you otherwise. You can't "buy" your way into a network anymore than "buy" real friends. Just because someone is a fellow alum doesn't mean they will roll out the red carpet for you if the only thing they have in common -- for example, just because the sons/daughters of the wealthy/connected/hugely successful happened to go to the same b-school as you did, doesn't mean you can just call them up and expect them to give you any more love than some random person on the street. That's the biggest fallacy quite a number of folks seem to make with these exclusive Ivy League type universities - just because you are in the same classes as the kings, queens and blue bloods, doesn't mean you are allowed in the same circles - and frankly, b-school is a far less exclusive place than undergrad (which is the true bastion of the rich kid network). B-school is full of mostly middle class and upper middle class folks who will end up mostly middle class and upper middle class - doing reasonably well medium- to long-term, but hardly "connected". It's about friendships ultimately, not networking. And friends who were friends first typically don't do business together.
But if the real reason you want an MBA is as a status symbol (but masquerading it as "networking") then you have to be honest with yourself that that's what is driving your desire to covet a top MBA. And decide whether coveting that status symbol is worth all that money. Not saying that is the case with you, but from the tone of your post as well as having dealt with many folks who seem preoccupied with brand -- more often than not it's the ego and lust for status symbols that predominates (primarily amongst Asians who seem to view educational brand as a status symbol more than anyone else -- it's like Asian Triple Crown - an Ivy League degree, a white spouse, and an unnecessarily gigantic house haha).
In any case, what I recommend is that since the prospect of b-school is a very expensive proposition -- you should invest the time to actually visit the schools, sit in on the classes and talk to students on campus - that's really the only way to get a real feel for whether this whole b-school thing is truly right for you - especially for a non-traditional applicant like yourself.
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