How many days will you be skiing, Wildcat?
Of your options, I've only skied Stubai and Zugspitze, and both early in the season. Both were fine, but I'm not sure I would want to spend more than a day at either given that they will not be fully open.
Stubai is the largest, but I would argue that based on recent snowfall and forecasts, Zugspitze may well have the best snow.
I would also agree that Kühtai may be worth considering. I have not been there, but my girlfiend has gone xc skiing there and said the downhill resort looked pretty good. It's at a high elevation, and may actually have a greater variety of runs open than the glaciers.
There is a free bus from Innsbruck to Stubai and Kühtai, but it is a PITA. Do yourself a favor and drive. If you are going to Stubai on a weekend, do yourself a favor and get an early start. The traffic can be bad.
As 131 says, if going to the Zugspitze, drive to Ehrwald in Austria, not over to Germany to Garmisch or Grainau. Are they really only opening on the 29th? That's criminal, but I'll believe most anything about the Zugspitzebahn GmbH. The German site (www.zugspitze.de
) just says they are "waiting for snow" (which the webcams snow quite a lot of) with no date listed.
Anyway, good decision to go for it. You'll have a great time. I wish I could remember the place we went to for apres in Innsbruck. It had a nice pub atmosphere and was right on the central square a little beyond the "Golden Roof". It's a nice city, but kind of lacks ski holiday atmosphere.