For anyone planning a restaurant or bar, this is a wonderful website. That part of the site gives layouts and sizes. For example, if your booth table is 24" wide, the booth backs should be 5 1/2' apart; if the booth table is 36" wide, the booth backs should be 6' apart.
Click on any of the furniture choices at the top of the page and you can find just about any style of furniture - and the measurements.
One of the most helpful sites I found.