I'm late to this conversation you have probably long since made your choice. We have concrete floors in our main stalls. Winters here are fairly mild and we change the hay bedding out every 2 weeks so our Nubians aren't laying on cold surfaces. The hard surface makes cleaning really easy, just rakes and pitch forks. Twice this summer we hosed them off we before relaying the bedding but even with that it's just a mornings work for three people.what should I use on the floor of the goat pen? What will be the easiest to keep clean?