I brought mine to open houses. If I liked it I did a weekday tour without kids.

Honestly my kid chose her preschool. There was a place she immediately got engaged and interacted well with the teacher. We chose it.

There was one school we were considering where she had an epic meltdown until we left. (My friends who toured separately all came back with bad vibes so I guess she wasn’t too far off). Another the interaction with the teachers felt a little off. And a third, highly regarded ‘elite’ school, where she hid behind me the whole time. I found that one chaotic and very rigid at the same time...

Kids have a sense about it.

Ask the school. I think most preschools have tours designed for parents only, so you can ask questions, listen, and focus. Also, you will be walking around the school and peeking in the classrooms -- your child may want to join them, but won't be able to, and may become frustrated.

Most people brought kids when we visited the schools. They usually had toys for them to play with during the presentation and it was easy enough to hold their hands during the classroom visits.

I would have felt really silly if I had arranged for childcare and 90% of the other parents were with their kids.

Ask the school. We brought our daughter and it went fine.

Please don’t, unless there are clear activities for the kid. When I was touring preschools, a couple of people brought kids and it really made the experience more difficult. They were disruptive and loud.