I was fortunate to have a drive-on lift at my disposal when I did mine - and I didn't use any lift points at all (just the tires on the lift).
I don't believe lifting the vehicle isn't a paramount for replacing the pans - many guys have done it in their driveways/garages with great success. Obviously, having the ability to get to every area in and around the work area is the best way to go, to ensure the best possible chance of repairing all the damage.
My experience is that having the car sitting on the ground with its normal stance is the best way to go. Lifting the car pretty much anywhere else (jack points, frame rails, etc.) can/will change the stress points of the unibody and potentially tweak the shape slightly while lifted (which should 'spring back' when lowered back down, provided nothing permanent was done - i.e., something major welded into position, like a roll cage or subframe connectors, etc.).
Judge is correct with respect to supporting the rockers - for the same reason as I mentioned above (the car doesn't normally have any support under the rockers, so it may tend to flex a little when that happens). Convertibles are more likely to flex, for obvious reasons, but the coupes and fastbacks should retain their shape.
If I were going to lift the vehicle for any reason, I would think the best place for that would be under the torque boxes, as close to rockers as possible. But that's just me, and I'm not an expert.
QCode351Mach (Scott) has some videos regarding floor pan replacement in his awesome '72 Mach 1 that are top notch, and he is an expert... and absolute perfectionist. Following his example will get you excellent results.
