I keep reading about the distractions of group meditation, but are there actually any advantages other than a feeling of togetherness?

Persevering due to a quiet sort of peer pressure. I've been on a few meditation retreats where you practice solo, in your kuti/room, as well as with the group in a meditation hall or chapel. I tended to stick out the prescribed times better with the group than alone. Ultimately there should be no difference but I think a lot of beginning and intermediate meditators will have a similar experience.

I've heard it said that meditating with your teacher is beneficial because the teacher can 'see' or 'check' your meditation. I'm not quite sure whether (or how) that's possible but I haven't ruled it out either.

I never meditated as "well" on my own as I did in a group. For a start someone else keeps the time for you. You don't have to check the watch yourself. Another thing was I was less inclined to stop the meditation session before my allotted time in a group. Meditating alone for me is very hard to ignore the restlessness and impatience I feel to stop doind it. The discipline of a group is the main thing for me.

Every few months someone posts a message on this forum about whether there's a meditation group or classes in Bangkok and Thailand. People always refer to the guide to meditation centres and monasteries which is pinned on the forum, but there's nothing in it that I've seen about meditation classes in Bangkok. It's only useful if someone's planning a 10 day retreat or a retreat in a monastery. Group sessions or classes are the best way to practise in my experience.