I have been storing in a closet that fluctuates between 65 and 75F for the past three years or so, for lack of a cooler place or fridge space. Any delicate hop character is gone or severely diminished within 2-3 weeks, I've noticed this on several APAs and IPAs. Next is the oxidation, which starts take hold after 4-6 months. Weirdly a schwarzbier that has been in there over a year still tastes fine to me, but my Maibock and traditional bock are both heavily oxidized. After about 10 months the maibock became completely undrinkable due to autolysis, and the traditional bock is approaching that threshold at 6-8 months (all bottle conditioned). I've also got a southern englsh brown in there that tasted fine last time I had it, about a year old, it seems that anything with some roast holds up better.
So I guess for peak freshness you've got about 3 months at these temperatures, and probably double that for less than peak but still enjoyable for your average beer. Roast character seems to extend that time significantly, and I imagine high gravity stuff will keep better as well. Hoppy beers, IMO, do not taste nearly as good after just a short amount of time stored warm, so keep these cold if possible. They are still nearly as bitter after a month, but the wonderful hop aroma and flavor is a mere shadow of what it was fresh. Finally, I suggest that you try to minimize the amount of yeast that gets into the bottle (cold crash first), this can wind up giving you some autolysis flavors way down the line, especially if the beer is particularly light or you've let in a lot of yeast.