1- will they let you do 1 full day. Lots won't, because it makes settling incredibly difficult, especially at that age. Ours is a minimum of 2 sessions (half days) on different days.
2- how long have the staff been there/ what is the turn over. They are 2 slightly different things. Ours has only lost 1 long-term member of staff in the 2 year's DD has been there, plus they haven't kept a few trainees they have placed from a local college. But there are 4 or 5 members of staff who have been there for less than 2 years because they've increased staffing levels.
3- how does it feel. I know it sounds mad, but really the nursery we chose felt right, as well as having tangible advantages.
4- how are the staff when you go round? At ours both the manager and the leader of the baby room knew DD's name. The manager knew every child in every room and interacted with them.
Friends looked around recently and were there at snack time. Their baby was invited to sit with the other babies and have a snack while the parents looked around and spoke to the manager/ key staff. That wasn't staged, it's what they're like.
5- examples of art work and pictures of children doing stuff etc on the walls, what toys are around/ out, what's the outside space like and how accessible is it? Ideally free flow.
6- anything in the ofsted that you like or that concerns you. Ask about.it.
7- how do they "discipline" children & does it work.
8- what split of rooms do they have (ours is 0-2, 2-3 and 3+) and how strict are they about.moving with age. DD has moved up early to preschool, because she was ready and all the children she plays with were moving. When she went up to toddlers they moved another child with her. They also sometimes move a staff member if a large cohort moves at once, to improve stability.
9- how do they manage the move between rooms? Ours does "play dates" for a couple of months, so a member of staff from their room will take a few children to the next room so that they can get used to it slowly.
10- what's the food & menu like.
Honestly though, ours just felt right when we went in. And it has been.
One thing I like is rheir new diary/ daily report books.
They've changed them so that now they have space to put photos in. So we get to see what the DC have done, not just a few words.