Width as in width per person? About 70cms will do.
For dining they use 60cm (2ft) width per person, but that doesn't count in hanging on your elbows and such.

I'm looking for a good depth... to have ample leg room for tall people and also able to push bar stools underneath when not in use.

Measure their upper legs when sitting on a chair, add about half their feet and there's your length :)

My guess is 60cms or 2 feet.

Is there a favorite bar you and your friends really like because it has ample room for long leg comfort? If so, I would take thorough measurements including the stools and go from there. Decide how many people you want to seat it.