The Tullibardine 1488 is slightly unique (as far as I know) as it is matured Tullibardine wash. Can't get a better nip and chaser! Is it worth the price? Nah - probably not. Buying the USP rather than a top quality beer. Having said that it is still a good ale.
I like the Innes and Gunn Oak Aged Ale quite a lot.
From the explanation I got, some kind of whisky is aged in these barrels, then the ale, then a second whisky. Not sure what the original whisky was, but the final product down the chain was pretty awful - the Grants Ale Cask whisky.