A few years go I sanded a stained table we had. Upon doing so, we discovered that it had really nice wood underneath. So instead of restaining, I applied about 4 coats of satin polyurethane. It looked nice.
Since that time, a few small spots have formed...typically from a wet spot when a coaster wasn't used. More recently, someone (cough kids! cough) managed to spill something on it and not tell anyone for about a day. As such, there's now a large spot down the middle where the liquid leached through the finish and raised the grain and flaked off the poly.
My initial thought is to get the sander out, sand the whole thing down again, and re-apply a poly finish. But is there anything else I should consider as an alternate DIY finish that can maybe stand up to daily use as a dining/homework/junk table in the center of our house full of kids? Or should I just live with the fact that it'd going to take a beating and that maybe I just need to re-apply a new coat of poly every now and again? If the latter, is there a benefit to add more coats that 4? Do I double the durability with 8, for example?