How different is staying in Palo Alto vs SF? And how long does it take getting between the two?

Palo Alto is a (mostly) wealthy suburban town next to Stanford U. Without traffic it is 30-40 minutes from SF -- twice as long when traffic is bad. There's a train that is lame by European standards but fairly good for the US, which takes around an hour, sometimes as little as 48 minutes.

Very.

Caltrain will probably get you between the two in somewhere between 45 minutes and an hour on a weekdays. Weekends, you're screwed. Trains run once an hour at the best of times, and are basically broken all weekend due to maintenance for the foreseeable future. (I think they're using buses to connect gaps in service on the weekends).

OpenAI is headquartered in SF?

That doesn't necessarily mean there are people working at their office in SF.

Others disagree: https://sfstandard.com/2023/01/13/what-is-cerebral-valley-sa...

This is good advice, people looking for AI people in SF take that first morning stroll through Hayes Valley.