Another key perspective is gusts.
20 knots steady is one challenge, 15 gusting 25 another.
Give me the former anyday.
F3G,
The thing to remember his is that you may not know what the gust factor is.
By ICAO convention, only gusts which are 10kts or more above the mean wind speed in a certain period (I think it's the previous 10 minutes) are reported.
So while you might be happy with 20kts, but not happy 15kts gusting 25, the 15kts gusting 25kts could actually be much better! This is because the 20kts could easily be 20kts gusting 29kts, in which case the gust factor won't be reported, becuase it's less than 10kts over the mean wind speed!
dp