Beer storage

[BenB]

Here's a somewhat tricky question- how long will beer be okay for? Are there rules of thumb for ABV and IBU? I would imagine those are the main factors here (assuming 12 degree cellar temperatures for storage)...

Clonebrews nicely gives peak and best before dates but is this predictable for other brews?

I'm planning some brews and want to brew some so there a few left for family members to try at Christmas.

I know my Moose Drool (22.6IBU, 5.2% ABV) in MiniKegs was dead after 5 months. It wasn't horrible but it had lost way too much hop character and tasted flat (even if it was crazily carb'd still). Such a shame The bottled Summer Ale I brewed in Februrary has also clearly peaked (albeit it's now mostly gone).
I'm doing a Dubbel next (6% 18 IBU) but I'm worried that's not going to be okay at Christmas. My gut tells me that strength and IBU level would be a 3-4 month peak, 5 month BBE beer.

I know it's subjective (some may prefer younger beers, other more matured) but is this kind of thing predictable? I might go for Plan B and brew an Old Ale now for Christmas.

[Rookie]

It depends on a lot of things. First off is abv and IBU level. A 9% barleywine with 90 IBUs will last a lot longer than a 3% mild with 20 IBUs.
Sanitation also plays a large part. I'm almost anal about cleaning and sanitizing all of my equipment before and after use.
Avoiding adding oxygen when bottling is also important.
I had a brown ale of 4 1/2% with 28 IBUs that was still real good when I finished the last bottle nearly a year after brewing.

[Bad 'Ed]

The biggest difference is temperature. They last twice as long for every 10c (ish). So keep half out and put half in the fridge for christmas.