Upload & Sell: Off
Mark, I would go with the 1280x720P size in MP4.
I run a popular pretty girl website and that size works best for subscribers of my site(s).
Highly unlikely that a serious photographer would still have a monitor set at 1280x1024. No need to be smaller than that.... and even 1280x720 would be fine for them.
I do see you say 250MB for about 90 minutes... thats a LOT of compression.
I would raise that up - maybe as high as a 1000MB (1GB). I have 6 minute clips that size on my sites but we encode as higher rates.
The goal is NOT a fast download. The goal for me, and I assume you, is a quality viewing experience.
Give me your email address by PM and I'll send you a PDF we give to subscribers about MP4 format and software for viewing, etc.