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 think the best thing to value or make some important to bitcoin is valuing it like the most thing you want in your life. Bitcoin gives many people a great opportunity to become more wealthy and it will stay and become more great when you value it.