I have the availability set to use the person's timezone who is booking the meeting. That works. But the reminder emails are sent with my local timezone. This is unhelpful, and a few people have commented that they thought they booked the wrong time and were busy. If the availability is shown in their timezone, the follow-up email should be as well. If the actual meeting timezone has to be theirs too, that's fine. I would rather do the mental math on the timezone than have my customers do it, especially ones who don't deal with calendars or multiple timezones often.