I recently had a new 24x34 garage built. I will use it as a shop and
for parking two cars in the winter. I'd like to have some kind of
ceiling in it, to reflect light down, and to keep heat in during the
winter.

Finished, painted drywall would look the best, but be difficult to put
up. I'd have to rent a jack, and I constantly be worried about the
jack damaging my newly painted floor. But I'm not worried about it
getting dented (as I've read here before) because my ceilings are
about 10.5 feet high.

But what are the other alternatives? Plywood? (OSB more likely). I
will be putting insulation in the 'attic', too. Not sure if it will
be bats or blown-in yet.

Also am thinking about what I should put on the walls... that will
probably be drywall, I think.

Thanks for any suggestions.

-Ryan