I pretty much do what everyone else does, except I don't feed in crates, and I don't separate them while they eat. At first I supervised to make sure that there was no food guarding or stealing going on, but over time I no longer bother. They can eat nicely a foot or two apart with no problems.
We have toys everywhere - they get put back in the toy box for vacuuming once a week, and they're free to choose what they want to play with. There are also several nylabones laying around. Typically, whatever one dog has the other dog wants, no matter if there's a duplicate in the same room. That's just how they play. As long as it's just play growls, I let them play tug and rip toys out of each other's mouths, which they both seem to delight in.
I did a lot of trading games with them when they were younger where they had to release something to me, and I'd give them a treat and then give it back, or I'd give them something else. Now, I don't bother to do that anymore, but they do need to sit and make eye contact before I'll give them anything, or at play time before I throw the ball.
The ONLY time they growl at each other (and I do allow them to do it) is with a high value treat like bully sticks. They always get them at the same time, but one always finishes first and not always the same dog. If the first dog starts hovering around the dog that's still chewing, a short growl gets the dog to back off. S/he will then lay down nearby with a big sigh and pout. I think that's fine. It's never escalated into a fight, and they only get high-value treats like bully sticks when we're there and are always in the same room with us while they chew.