exiting the first cave in sagada, still underground you pass through a small inlet that you have to climb into to get through sumaging cave, at the entrance of sumaging cave, you enter a great big hall where giants could live inside by the height of its ceiling (it is high enough that light from our lamp could not get to it), how would the giants get in, i would not know.
i have not been to many caves around the philippines, but i would definitely recommend spelunking in sagada, its a good two to three hour adventure, even with a guide, your heart would literally be pounding when trying not to fall or slip on the semi-dangerous slopes and passageways.
i would recommend getting to sagada from baguio, then you can extend you trip to banaue, you get most of your trip that way compared to taking the baguio - banaue - sagada route.
from manila, bus leaves for baguio mostly every hour during the day (they also have night and dawn trips) at the victory liner bus station in cubao, quezon city