So far they are cohabitating nicely.

They've doubled in size in two weeks. I don't know if I am happy or concerned.

Now THAT's a good-size pot for huge spider plant roots. I think you'll be happy with that, and that the plants will be happy as well. I've paired spider plant with many companions and the only problem is that the spider plant roots are so big. Starting with babies like that, it will take a quite a while for the roots to get huge and fill the pot. I love having short plants as a lower layer if a lot of soil is visible like that. The more companions, the fewer pots.

I agree. Be warned, I have had spider plants choke its companions before

I intend to remove them when they get to a certain size. I have a pot with some annuals in it, when they shuffle off the spider babies will have their own home, and the peace lily will get a new companion.
I was thinking creeping jenny. It's annual in my zone, might make it inside over the winter but i like the idea of it dying off and being replaced with whatever strikes my fancy. That's the only pot I have that's big enough to play with like that, so I can justify the expense and energy.

That all sounds like tons of fun- good luck!!