When I did my IR in the US with a collection of five US pilots they all used WX-BRIEF for every flight. The same raw information is available from
www.duats.com as is the ability to file the flight plan. I used a mix. As you said, you want to be able to do your initial briefing from your hotel room; when I could I used duats, but if I couldn't get dial-up or wireless connectivity I would call WX BRIEF.