If you don't mind a little brett funkiness; a beer bottled with live Brett (and quite a bit of residual dextrin sweetness) should age well and change considerably over time as the brett will stay alive slowly eating the remaining sugars.
-I'd be taking that barley wine of yours, or really any dark strong beer and adding a bit of brett before bottling. (If you don't like the typical brett flavors, brett clausenni produces some very mild and pleasant tastes but still can have massive attenuation and continue working for years.)
Actually, the 30 year old Westmalle tripel I had was amazing, so it's not just the dark beers that age well; strong seems to be the only pre-req.
(In 4-6 weeks I'll be ready to blend my Industrial Rev Porter and I'll have some brett dregs I could mail to you, but it's a more funky lambic strain...)
Alaskan Smoked Porter is supposed to be an absolutely fantastic beer to lay down and age for a while; so I'm guessing any stronger smoked beer could be very interesting aged for a while.
I had a SUPER oaky beer that I laid down for 2 years -Great Divide Yeti Stout- Barrel Aged, and it mellowed some and turned out really fantastic, so I'd recommend any really oaky beer, too. Innis and Gunn have a couple barrel aged versions out that go beyond their normal oak aging and are then aged in a rum barrel for a while; could be interesting to age for a while (only if they up the ABV over a normal Innis and Gunn...).
Adam