rule of thumb, the lighter the wine, the sooner it fades. Rutherglen makes some wonderful heavy sweet wines(not expensive either). one of them will last a month without decay. some huge ugly reds are actually better the second or third day. most delicate whites lose that delicacy even after 4-6 hrs, and just become tasteless.

if you take a big red, fill it to the top with more big red, then pound a cork back into it, it will keep right on going. a couple of the bordeaux firsts have a "recorking" program. they put a younger but similar wine in as they recork. and as i said, they fill to leave little or no air.