Thanks everyone for some great suggestions. I went to the local Tractor Supply and ended up buying Weaver slow feed hay nets. I would have preferred the Shire’s net, but they only had it in the largest size. I like the idea of a hay bag better than a net mainly because it looks like it would be easier to fill, but I decided to start with a hay net instead simply because of the price difference. The prices on those bags make me swoon, but if they hold up better over the long run they may be worth it.
Another reason I started with the cheap nets is that I need to decide whether the horses need a 1" or 2" hole. I bought the 2" size, but if they still eat the hay too fast it won’t cost too much to go to the 1" size.
I wish I could still get the bluestem hay they used to eat. It was nutritious but not so tasty that they ate it too fast. There was always a little left in the morning, so I knew they had hay available all night.