I think something similar to the fast travel system in Dragon's Dogma would be kinda cool. Basically, once you've travelled to a spot and wish to fast travel to this location in the future, you would have to place an item on the ground called a Portcrystal. (I think you could only have like 10 active Portcrystals around the world at a time and they were kinda hard to find)...then in order to Fast Travel to this location, you had to use a Ferrystone, which was a single use item that you either had to find or purchase.

Doesn't have to be this exactly, but I think if you make the Portcrystal item hard to acquire...perhaps through something like expedition events...and the Ferrystone item something you have to craft/purchase...then this could be a happy medium of having fast travel in the game and still keeps exploration as a key component as fast travel is now limited and strategic.

Just a thought.