As of now I don’t think the Big Hole is going to produce very well, they are getting a lot of run off. The Beaverhead would be a good option. The entire river is now open. This is good because you will probably want to stay on the upper stretches. The more water that comes in the dirtier it will get.
Check out this link for the Madison. Don’t fish the Madison much but when I do these guys have been pretty reliable. Looks like most of the fishing is up by the lakes.
The missouri below holter dam and down below craig montana is fishing very well, People come from all over the united states to fish that area with guides.. You can rent a drift boat at crosscurrents in craig.. Its a tailwater and bugs are tiny.. Most places below a dam could be fine. Call crosscurrents or montana flygoods in helena for information.. Canyon ferry was really hot recently, dont know if it still is or not.. Memorial day weekend is approximatly the peak for greyling in park lake..