Hi Gillywhich,
I have never been good at remembering names, faces yes, but not names, so I prefer a smaller group - 30 max - so that I have a good chance of remembering at least half of them.
When deciding on a tour it can be worth while ringing the office and ask them what the maximum size of the group is likely to be. I was told 30 for one tour, but it left with 38.
Sylvia