I think that the most common way to value Bitcoin is like valuing other currency by another currency.
Seeing to it that we all know all the factors that causes or affects supply and demand equilibrium.
Also the time we hold bitcoins. Time is very important factor.
I hope that everyone of us think the way you think it the way you value bitcoin. But as far as I observed people doesn't value bitcoin like valuing other currency by another currency which is not observable because the time that bitcoin goes up people grab this opportunity to sell all their bitcoin without thinking what happen next.