That's funny I'm torn between three mile and east of missoula. I know that place east of zoo town should be dry, three mile on the other hand has lots of shade and will more than likely be snow covered. I have only driven up 3 mile and saw some spots that would be good to hit with the hand dredge. I want to check it out this summer though.
The best advise I can give you is when you first start out looking for gold is don't break you back moving a ton of dirt to get a little gold. Instead cherry pick spots. Hit the spots that people can't get to like cracks and old steam beds. You would be surprised how much gold you can find by snipping.
You get into bed rock cracks that haven't been touched and that's when you can find pickers and nuggets.
If you have questions if a place or area is any good shoot it by me it may save you some gas money. I spent all last summer checking places out.
If you want to find some color and if Florence isn't to far for you and your wife check out 8 mile creek. When you get up there you will see where people are digging. I have found gold every time I have gone up there.