I would like to recommend a flight planning weather website that I consider to be the best of them all. It was originally recommended to me by Scott (Airfox) and I have been using it ever since.
I often suggest it to other pilots and am surprised at how many of them are unaware of it. Maybe most of you already use it, but if not, you should give it a try.

This one website has a ton of info and it takes a little effort to learn how to navigate it, but is well worth the effort IMO. It has wind and gusts from surface to any altitude; clouds, cloud base and tops; temp/dew point at any altitude; visibility; icing altitudes; rain/snow; pressures; animated radar; airport Metars; all of this from present time out to 9 days forecast. This for the whole US and it looks to me like it includes the whole world wherever there are weather reporting stations. I used to click thru 3 or 4 websites to gather all this info. Scott and I have found it to be quite accurate. I'm sure it uses its source data from the National Weather Services, the same place all other websites get their data; but it puts it all in one place.