Word of mouth is very important too. The internet is a huge source of info and if a ranch is crappy, somebody is telling a story about it somewhere on the net. On the other side of that coin, if a ranch is really good, people are telling those stories too. Look for a ranch that has repeat customers. I'm afraid there are a lot of crappy ranches out there that operate on the assumption that you are never going to come back to their place no matter what they do - so your happiness with the hunt isn't overly important to them.
Size certainly matters, but maybe not as much as how well run the place is. The ranch I recently went to was only 120 acres. My initial thought was that is too small. But since it was bowhunting only, that was actually more than enough - the game could still easily elude you, and did most of the time. The ranch owner is wise to limit it to archery because gun hunting would be too easy.
I don't know that there are many places where the game is only naturally reproducing - I think most all of them are going to have to supplement that slow process. So, another question might be how often is the herd added to.
