I was actually just giving this some thought. Here's where I'm at.
St. Louis - They have a bunch of RFAs they need to qualify. Risto for Schenn and a pick/prospect. Schenn is about the same salary and has one year left on his deal. St. Louis gives us a pick because Risto has term whereas Schenn is basically a rental. He's a good stop-gap 2nd line center. Maybe the return is higher if we also take another cap dump. It could also be Risto for Perron depending on the NTC.
Vegas - I'm not sure on this one, mostly because I think Risto is too clumsy for Vegas' style of play. I think they might honestly want someone with more "jump", but they need D and Stastny would be a good return for us.
Anaheim - They need D and they have a TON of forwards. They aren't in cap trouble this year, but they will be next year, so they might want to move some money this year so they can handle their RFAs next year.