Our front yard has a concrete rectangle for the center with planter box around it. We are thinking of removing the concrete and replacing it with garden soil so it would be converted into a lawn. During summer, the heat is somewhat unbearable in the terrace that is fronting the concrete garden. However, we are hesitating because our dogs are used to the concrete and they may be alienated by the grass. That concrete is their toilet for now. Part of the renovation is the redesigning the planter boxes so the decorative stones will be removed to give space to more plants. Maybe we can do this renovation early next year... if our budget permits.
Having a lawn is much nicer, but it's a lot of extra work. The people who look after our garden don't take good care of ours and it's full of weeds. I'd still rather have that than concrete though. I doubt your dogs will be alienated by the grass. Once they get used to it, I imagine they'll enjoy it more than the hot concrete.