I cook round roasts all the time. I've done rotisserie, indirect on the grate and on the WSM followed by a quick sear. Like the thread above cooking to medium rare in the deepest portion and sliced thin is the way to go. Usually only takes about an hour or two at 325.
With thinner cuts of the round I score the exterior about 1/4 inch deep and marinade with some soy, Worcester sauce, red wine vineger and various herbs and spices. Scoring it gets the marinade in a little deeper and adds some crispy edges. After removing from the marinade I usually put black pepper and paprika on it for some extra flavor.
It's usually tender enough to feed by 1 year old in small pieces, one of her favorites!