I'm faced with a technical conundrum regarding what I want to do creatively. I'm setting up to shoot doc interviews with the following setup

A cam is Panasonic AF100 shooting AVCHD @ 1080p
B cam is (maybe) Panasonic GF1 (hacked) shooting AVCHD @ 720p

Whether or not I have the 720p B cam isn't really so important to this question, what matters most is how the image quality of the A cam is ultimately affected by the editorial workflow.

It seems that every (AFAIK) distributer/broadcaster has delivery specs requiring the master be 1080p. So, with that in mind, what is the best way to approach my creative needs/wants within the real constraints that I have?

My intention is to shoot with reframing in post (likely in Motion or After Effects) in mind. If the source is 1080p and the master has to be 1080p, should I:

A: take my 1080p source footage into a 1080p timeline, where reframing will certainly entail blowing up the image more than 100% (as much as maybe 120-125%)?

B: take my 1080p source footage into a 720p timeline, where reframing will likely not entail blowing up the image more than 100% (or little above 100%), and then upres the output to 1080p?

It seems to me the final outcome either way will be that the 1080p source is being scaled up beyond 100%. So pixels are getting stretched either way. In fact, option B has source being scaled down then back up again, which sounds really abusive now that I am typing all this out… ;-p

There is also one more option

C: take my 1080p source footage into a 720p timeline, where reframing will likely not entail blowing up the image more than 100% (or little above 100%), and output to 720p and let the distributor upres if they really require it be 1080.

Thoughts? Tips?

I don't understand why you would want to do that. Why reduce the quality of your final product and spend extra hours in post when you could just spend an extra few seconds on set properly composing the shot to begin with?

I skipped over explaining why I want to reframe. It isn't a matter of not "taking the time" to "properly" compose the shot, what I am looking to do is to be able to add some variety to the framing of the interviews without interrupting the flow by constantly changing lenses (I'm opting to use my faster 50mm or 85mm prime lens than my slower zoom lens, for both creative and technical reasons) or camera positions. The idea being to frame for a medium close and add some motion in post to either simulate a subtle trucking motion or a push in, or cut to a closer framing when dramatically appropriate.

So there is a creative motivation for doing things this way, greatly influenced by my shoestring budget (iow, multiple cameras are not an option… the possible 720p B cam I mentioned is contingent on getting it cheap off craigslist, which means I likely won't have it).

Make sense?

If my destination was just for the web, I would just do it all in a 720p timeline and output 720p… but if I want to deliver for broadcast or even iTunes, Netflicks, etc… 1920 x 1080 is what is in their delivery specs (despite internet services currently streaming at 720p).

It seems that every (AFAIK) distributer/broadcaster has delivery specs requiring the master be 1080p. So, with that in mind, what is the best way to approach my creative needs/wants within the real constraints that I have?
Sounds like you're starting with a speculation rather than certain knowledge. Why not confirm first what exactly your distributor expects, then go from there?

Your workflow may also depend on your NLE... some handle down/upscaling better than others.

If I were you, I'd work with a 720P timeline, and output a 720P master; if the broadcasters needs higher resolution, let them worry about upscaling - chances are, they have much better tools to do that.

I skipped over explaining why I want to reframe. It isn't a matter of not "taking the time" to "properly" compose the shot, what I am looking to do is to be able to add some variety to the framing of the interviews without interrupting the flow by constantly changing lenses (I'm opting to use my faster 50mm or 85mm prime lens than my slower zoom lens, for both creative and technical reasons) or camera positions. The idea being to frame for a medium close and add some motion in post to either simulate a subtle trucking motion or a push in, or cut to a closer framing when dramatically appropriate.

So there is a creative motivation for doing things this way, greatly influenced by my shoestring budget (iow, multiple cameras are not an option… the possible 720p B cam I mentioned is contingent on getting it cheap off craigslist, which means I likely won't have it).

Make sense?

Shooting with something like a slider will allow you to add motion or change the framing of a shot on the fly.

Given the options you present, I'd do it in 720p. But keep in mind -- when you push in, you will see a difference in the footage between that footage and the footage you keep full-frame, not least because you will be making any video noise larger in proportion to the frame.