Grangestone Bourbon, Rum, Sherry Cask Single Malt Scotch Whiskys

While browsing the miniatures at a Florida Total Wine - which are so superior to Virginia based stores since spirits are sold -- I found a trio of Grangestone Single Malt Scotch Whiskys each spending a second maturation in a different type of cask.  The Grangestone brand is a Total Wine house brand that internet sleuths have most likely linked it to William Grant and Sons and produced at their Kininvie distillery.  William Grant and Sons was founded in 1887 and has grown into the third-largest producer of Scotch whiskey behind Diageo and Pernod Ricard. They feature brands such as Grant's, Glenfiddich, and The Balvenie.
Alone, Grangestone should be considered a mid-tier brand where the initial finishing occurs in traditional American oak casks for three years in order to be regarded as a "proper" Scotch whisky. But finding a trio of miniatures that underwent a second maturation in bourbon, rum, and sherry casks provided an opportunity to see how each imparted different characters into the whisky. As stand-alone 750ml bottles, these whiskys sell for $30, but as miniatures $2.50 each.
Overall, I preferred the Grangestone Rum Cask Finish Single Malt Scotch Whisky as it seemed to impart more balance and depth with vanilla and a rum-honey sweetness. The Grangestone Sherry Cask Finish Single Malt Scotch Whisky was the most concentrated with plenty of baking spices, dried fruits, and caramel.  Finally, the Grangestone Bourbon Cask Finish Single Malt Scotch Whisky was very spicy - almost rye spicy - with more burn and oak flavors. Ready for another round...