is it worth risking a week of -10 weather at steamboat, or no new snow?
the weather is a crap shoot in any ski vacation. pick the best mountain and in that regard steamboat shouldn't even be in the discussion.
this is such a silly discussion... may w/b vs jackson hole, tahoe, utah... but steamboat, that's just crazy.
Weather at Steamboat, or any Colorado Summit/Eagle resort is not a crap-shoot. You'll almost always have dry snow, and (often), sun. Colorado receives more than 300 days of sunshine per year.
What's "best" isn't based solely on terrain - although it may for you. Steamboat's terrain, while not in the epic class of JH, The Bird, or Whistler, is still plenty fine.
A "crap-shoot" is investing $$ thousands on a family trip to Whistler, and betting on no rain or fog. Many have made that bet, and lost.
Whistler is a bit like Vancouver (where I was raised). When the sun shines, it has no peer. The views are spectacular and your options are vast. When it doesn't, it can be a long, gloomy trial.