What if more Dragons survived?

What if a few hundred dragons besides the ones that we know of were able to escape the Doom of Valyria without riders and migrate to various places in Westeros and Essos? Where do you think they would settle? How would this affect the timeline of ASOIAF?

I feel like they would prefer to take residence in caves or mountains. Obviously the Vale is probably a good mountainous region for dragons, but which region of Planetos has dragon-quality caves?