I've only been to one tasting room and it was pretty much like being in a bar. They had all of their various beers available on tap or in growlers with snacks Pretzels, chexmix placed around at tables and at the bar. My question is are all tasting rooms like this or are some similar to a gift shop where you can only take home a growler?
I think you'll find most breweries will serve 2-3 oz pours for most of their beers, but it may depend on whether you paid a fee to tour the brewery for what or how much you get. Snacks have been available at some that I visited, and some not. There is always beer available to go from what I have experienced at the 5 places that I've been to. No, maybe I'll take that back - no beer was sold on the way out at Budweiser in St. Louis that I can remember. But maybe I wasn't looking for any.