Results from my tea tasting:
Sassafras root is one of the main traditional root beer flavors, and I'd say the sharper component of that familiar taste. I don't think it's actually used anymore due to something in it being mildly carcinogenic in large quantities in small animals.
Sarsaparilla root by itself has a very fragrant, round, fluffy smell, akin to vanilla. It was less intense in the mouth than in the nose. Very root-beery.
Cherry bark made a quite weak tea. Obviously smells like furniture being made out of cherry wood. I think I can use more than in the last batch without risk of bitterness.
Birch bark was stronger than cherry, very nice, should probably use a lot.
Pine bark is nice, but strong. Probably use sparingly. Might be good with wintergreen (which I don't have.)
Licorice root was super sweet after it sat for a couple hours. Less so when it had only steeped for half an hour. Probably good to use to make low-sugar drinks. Some aftertaste, but not unpleasant.
Sliced stem that I thought might be American Ginseng had an even stronger non-sugar sweet than licorice. Definite aftertaste. I don't think ginseng is supposed to be sweet, so who knows what it is. As long as it isn't dried sea cucumber.
Yellow Dock root tastes like digging up green roots. Green, earthy taste. A little bitter.
Barberry root had a very mild, light wood taste.
Burdock root reminds me of a midwestern stream, or some wood used in boat building. Pretty bitter, maybe offensive to some, but probably adds some good complexity.
The flavors were less discernible once cooled. Putting a pinch of sugar in each didn't hurt, but adding ice and club soda wasn't as helpful as I thought it would be. It mostly just watered the flavors of the teas down.