Here's a few ideas from two of my favorite Kindergarten teachers:
"I would love to know the answer to this dilemma. What has only worked for me is me assigning spots to kids and varying it up so that it feels like it's a variety. Another option may be offering specific spots for specific tasks like listen to reading in a certain spot read to self in a certain area, work on writing in a certain area. etc. Another idea may be to actually physically give them a dot or a spot and have them place it down and it has her name on it and they have to stay with it. Just thinking out loud."
The other teacher said that she releases kids in waves so that they can get their spots before the next wave of kids goes out. She's also had a lot of discussions about what is fair as far as who always sits in the cozy spot etc. and she says that has helped.