I've never had any problem having the airlines not put me on the next flight. I've never tried anything more than a day and a half later. I've also had them change airports relatively significantly (TYS to CHS) before because that's where I was going to be driving to, and I would've missed my ride. They're pretty willing to help you out and accomodate you when you're volunteering, at least in my experience.

Edited to add: I even have had them book me on MR-style routings before. For example, I was bumped off a TYS-DCA nonstop. I then was rerouted TYS-CLT-BOS-DCA. Another time, I was flying DCA-PIT-MEM. Volunteered for a bump in DCA. Ended up flying DCA-LGA-CLT-PIT-MEM. Was nice for the extra segments and miles.

[This message has been edited by kreeft (edited Mar 02, 2004).]