Sample email sent 2 weeks before the tours to confirmed groups.

Hello Renea,

        Our current schedule has our first tour group arriving at your
stop at 7:30 PM on September 7th.  Based on past experience, we think that
a stop at W91 should last about 30 minutes, but you're in a much better
position to judge this than we are, so feel free to ignore that
information and give us a better estimate.  Let us know as if that
particular time works for you.  If the schedule changes, we'll send you
email.

        The second tour group (if it exists; we might combine the two if
size permits) will show up around the time that the first group leaves.

        We would like to have a phone number that we should call that
night (if we're early or late or need to be let in) and the location
where we should meet you when we arrive.  Our guest speaker, Jeffrey
Schiller, will be speaking starting at around 10:00 PM in 4-231.
Thanks for hosting a stop,

        -Tim Abbott