Re: Which one? Estes Park CO or Big Sky MT.
Having lived in both places, I vote Big Sky - it's prettier and the fishing will be just as good that time of year. The Poudre is probably gonna fish like **** for a long time after the fire(s) last year... the Big Thompson is ok but not my fav... I dunno.
That having been said, there' a lot (a... lot) more for a non-fisher to do in Colorado - so take that into account.