I've previously requested a synth constructed entirely|primarily of spherical panoramas http://bit.ly/psfmsps + Joscelin T has already requested a Walk synth where a parallax panorama is taken at each step along the path. http://bit.ly/psfwpst
Those would be my first and second choice, but if either of them is too challenging or is going to take too long to bring to fruition, then I'd ask for something simpler: namely a walk where the entire distance traveled is shot in both directions: from beginning to end and then from end to beginning so that the user is at least able to turn around and head the opposite direction.
This does introduce even shorter paths than the current 200 photo limit because now the 200 must be spread over the round trip, rather than a one way.
I anticipate an answer along the lines of just shooting both and uploading individually and waiting for synth linking. I just don't know when that will ever happen since Read/Write World disappeared.