Show selected folders size at bottom of finder - like you can in Windows In Windows, it's easy to grab a bunch of files up to a size limit.

Just keep selecting and look at the bottom of explorer where you can see the 'selected files combined size'

There appears to be no way to do this in finder except for option + cmd + I, which means you have to keep redoing it. You don't get it in the 'dynamic' style like you do in windows.

What's the workaround?
The Inspector has this functionality in Finder. Instead of Command-I for get info, add the option key to use the inspector and select multiple items to get a quick summary of space (Command-Option-I)

The inspector window is dynamic and summoned with these keys ⌘ + ⌥ + I

A brief history of the get info and inspector is maintained here.