I’ve done some great MTB rides across Scotland, The Alps, Whistler, Banf, Morocco, Trinidad and a bunch of places across the US. I’ve found companies that do guided MTB tours and hooked up with them or more recently, like Whistler and Park City, gone to places with well mapped trail networks.
I met a couple of guys from Oregan during a MTB tour in Scotland which led to trip to their neck of woods to ride McKenzie RIver and other local trails.
The big reason why to go somewhere completely different to go ride is to meet interesting people, those on the ride and those you’ll meet along the way, and to see an area from a very different perspective.
Make sure to travel with a decent company and if possible take your own bike. Renting can be ok, but I’ve always found I miss not riding a bike I’m used to.
I’ve been looking at sacredrides.com recently as them seem to get good reviews and run tours in some interesting places.
Oh and save up and spend the money. It’s not going to be cheap, but it is going to be worth it.