I’m not one to be able to keep beers for a long time, let alone long enough to age. One of the few good local beer shops has been having a sale recently and a LOT of the stuff is just no-go, but they do have some darker stronger stuff that would keep or age, and it seems they are storing the stuff relatively well. The two I purchased, and their reviews:

Sierra Nevada Bigfoot Barleywine 2017
Packages 23 Feb 2017 Drank 16 August 2019.
Aroma is very rich, caramel, burnt sugar, dark fruits, plum pudding, prunes, figs, pumpernickle bread, malty, lovely.
Appearance is a dark amber, slighly cloudy, slightly tan-ish head thats quite thick and lingers leaving thick tan lacing.
Taste is initially a boozy indecipherable hit then straight into a big broad bitterness, bitterring hops and grapefruit pith. Then cocoa, burnt sugar, dark roast and black malts, a cognac-like boozyness, coffee grounds. very malty, very rich, no sweetness at all. Very big, very full on, then it subsides leaving a hoppy bitterness on the tongue before it becomes cloying or overbearing. That hoppy bitterness just lingers on.
The mouthfeel is surprisingly light, slight viscosity that fades and a light carbonation.
I do not usually enjoy Bigfoot very much when i drink it fresh – the year its made. I was lucky to find this at my LBS and its the first time I have had a barley wine with a few years on it. This was fantastic.

Sierra Nevada Barrel Aged Maillard’s Odyssey 2015
Bottled 2015 Drinking 21/8/19.
Aroma is complex, rich, hazelnuts, cocoa and, dark roasty malts, coffee liqueur, rich fruit cake. Appearance is dark, opaque with a lingering though thin, tan viscous head.
Taste is boozy, sweet, bitter dark malt, cocoa powder, chocolate, coffee and coffee grounds, vanilla, burnt sugar. Theres some oaky dryness. Any hop bitterness is very mild. Theres a fair bit going on though it is very smooth and rounded. Complexity increases as it warms and opens up adding red wine and dark fruits, the oakyness increases in both taste and smell. Mouthfeel is quite watery, theres a viscosity to it, low carbonation.
This is very good. it has aged well.