I'm quite partial to fields and lakes, but more than those, I really enjoy the little areas found within. For instance, I've always loved the fishing hole, especially in TP. That was probably the most beautiful area of the entire game. But then I also like the little spring in OoT's Lost Woods, as well as the little area at the entrance of the Forest Temple. The little fairy lights, the trees... so serene.
I guess I just like the more peaceful areas. The lakes seem to hold a romantic feeling, especially OoT where you could watch the sun rise and set. The forest seems to be an area where one could enjoy a moment of tranquility and solitude.