Well the only thing with turf is that unless its a moveable run it will be impossible to keep clean. What is the surface currently? I would personally go with slabs or concrete that should you ever need to you can wash it down and bleach it etc (since mine have some mystery bug I'm very conscious that I need to be able to do that on a regular basis). The other thing with turf is that if its on soil they will be able to burrow out/ predators can burrow in, so you would either need to sink the run in quite deep or have wire laid under or over the turf to prevent that.