Sella Ronda is about 40 or so kilometers - either direction. And it is 1200 km of pistes on Dolomiti Superski Pass. Not all connected, some short bus rides required here and there, but nevertheless great area to ski and often unfairly viewed as "mellow".
I just think it is the opposite - because of huge numbers of intermediate skiers attracted to groomers, stashes of good snow are left untouched for days. Val chair in Selva serves some fairly steep(ish) terrain with nobody on it for hours, you can follow your own tracks lap after lap. Glad to see them getting some snow this year. Truly spectacular area, well deserving of UNESCO World Heritage Site.