October can be great, but it's also the biggest gamble of any month of the year. We get lots and lots of precip in October/November but by November the majority is falling as snow so the rivers generally stay in shape. That being said, there are still plenty of dry fly opportunities in October if the conditions hold, and fewer (I haven't fished a dry in Nov.) dry fly opportunities in November. If you can keep your month flexible until you have to go, I'd wait for the conditions to set up, have a decent forecast for the next 2-3 days and pull the pin at that moment. Not sure if that's a possibility. The other factor at play - are you drifting or driving/walking?
Early-mid October you're fishing for older summer runs generally... late late October - November you can get fresh ones (early winter/late fall fish) if you know where to go. I'll let someone else name the rivers - I'm sure that information is in this forum somewhere anyway.