I traveled to Washington DC last week for a conference. It's not the first time I have been to Washington DC, and one of the things I really like about the city is its Metro system. It's a subway system based on San Francisco's BART station. It goes to pretty much most places you need to get to so it's pretty convenient. Although Metro is pretty efficient, it's still public transportation so taking Metro takes longer than driving.
It turns out, even though I love Metro system, that I would rather pay a more to arrive at my hotel (especially at night), faster than I would by taking the Metro. After a long flight, the time spent waiting to take the Metro is worth less than the money spent on taxi. And it's money I don't regret spending.
So time is money, and all you need to do is figure out what is more valuable to you -- time or money?