blawder wrote:...so we can taste the difference that just the wood has made on the product.
As others here have intimated, this isn't going to be quite so simple as it may at first seem. The principal difficulty stems from the fact that many distilleries with a fairly wide range of different age offerings subtly (or not so subtly) alter their cask regimens for their various releases.
I have to wonder if the two Aberlour choices will give a clear picture of how age alone affects the spirit in the bottle, the problem being that I find any sort of wood finishing technique employed tends to cloud the age factor by introducing a 'polishing' factor into the equation. Ditto for sampling the Laphroaig 10YO versus the Quarter Cask; the latter is (I find) quite distinct from the rest of the distillery's lineup. Perhaps better (as has been recommended) to opt for the 15YO or 18YO (depending on local availability) to pit against the 10YO.
With the Glenfiddich 12YO and 18YO, one runs into a subtle change in cask regimen, as the older release seems clearly to display a greater influence from ex-Sherry cask maturation than the younger version (which is much crisper). Likewise with the 12YO and 17YO Old Pulteney bottlings.
Highland Park may represent your best bet, though even here there are 'transitions' in terms of the relative proportions of ex-Sherry American oak and European oak utilized for the different ages (never mind the varied use of first and second fill casks).