SAP has offices in Palo Alto. Like most large corporations, 40 hrs is the norm. When I was there, vacation was determined by tenure. 3 weeks to start, 4 weeks after 3 years, and 5 weeks at some point.
And they definitely encourage vacation. For accounting it's considered a debt, so they want everyone to use it up to improve financial results. I imagine most public corps have this attitude as well.
As far as asking and not sounding lazy in interviews, I tend to ask something like "What's life like working here?". In one of the interviews you're sure to find someone who will give you a candid answer and you can segue into more direct questions if it feels right.