I would put the table cloth on the table and test how you like it with each of the ways you are considering doing it....with batting, without, how thick.
Some questions to ask:
Do your glasses tend to lean when you have no batting in it?
If yes, does adding batting help?
Are you going to add a clear plastic cover so that it won't get wet and dirty too quickly?
Is it just for show?
We'd love to see a picture.