Artists who have a minimum (like we do) are booking exclusively your group for your event that day. Artists who do not are working with several clients around town that day. Of course you could do a salon setting, but then you’ll have separate appointments and a less cohesive feeling for your group since you can't be lounging in robes and sipping champagne.
If you are getting ready at a hotel, you have to book a big suite that can fit a large group and you need to ensure the room has great natural light. We've seen too many small rooms with romantic lighting and no room for the group. On top of that we are often doing back-breaking bending down to short banquet chairs that were brought up from the hotel event spaces. The room needs to be booked for the night before and night of your wedding in order to not deal with having to check out during getting ready time. And make sure you assign someone to cleaning up the room after you've wrapped getting ready. We've left many hotel rooms after the flurry of girls getting ready and it's really sad to see the leftover food and dress bags strewn about... and that's what the couple comes back to after the reception. If booking a hotel room, just make sure you're in a wonderful space and that clean up is covered.
If you are getting ready at your venue, make sure the room fits your needs as mentioned above regarding lighting and space. You will also want to chat with your venue coordinator about fees associated with getting in early (there are often additional costs for things like starting at 8am for makeup instead of coming at 2pm for pictures). Make sure you know about any catering rules (i.e. many venues will require you to do catering through them rather than any outside food/drink). Some brides love the convenience of just being in one place for the whole day! But do make sure you know if your things can stay locked up in the bridal suite that day, or if there is a cap for when personal belongings need to be out of the room.