Speaking as someone who has never been in your situation... I can't help but draw the parallel to what this would look like if this were two individuals rather than two couples feeling this way. One really wanting to get together again, the other unsure. Wouldn't the answer in that case be pretty clear -that they needed to get to know one another a little better before having sex again? I'd vote for the 4 of you, and parts thereof, spending some more time together doing other things, including talking but also just ordinary clothed fun. Dating, sort of. Then the other couple isn't getting a complete brush off, but your wife gets some time to figure out how she really feels about them, and what she wants (and you do too). Put on the brakes, since no one knows which way to steer.
Also, please turn your wife into a "giggly, quivering multiorgasmic mass" asap. The world needs as much of that as possible!