Storing wine @ room temp vs in the fridge?

What is the solution if you drink half a bottle of wine, but cannot bear to throw the rest of it away? No wrong answers here: drink it the next day, cook with it, use it as a marinade, the options are endless.

Let's focus on keeping it for the next day(s). Does one use the cork (or screw top) that came with the bottle? A Vacuvin? Some other fancy device? Again, lots of options. Growing up, it was pretty common for us to leave a bottle of red with its cork in, for consumption the next evening. "It's like the French with their butter," my father would tell me. No need for refrigeration if you consume it quickly enough.

To compare apples to apples, I decided to drink two half bottles of Cannonball Cabernet Sauvignon with a few friends (thanks, Yoav!) and to keep them for two days before finishing them. One of them, I put in a fridge, while I kept the other in a cool dry place (~18 degrees Celcius). A friend and I helped each other blind taste the wines after both days, pouring each of the wines for each other and letting them come to temperature, covering the glasses with plastic wrap.

For the results... 

Father was wrong, at least according to my small sample size of two over the course of ~47 hours. The room temp wine was more acidic and overall much closer to vinegar than the refrigerated wine, per expectations from Chemistry. Perhaps two days was too long? 

Does anyone have any favorite tools that they use to preserve wine if they don't finish it in the first go?