hey there. I'm a Filipimo and a traveler too :) You've got great destinations. In Palawan, you could also check out El Nido (6 hrs ride from Puerto Princesa). It's another stretch of white beach. If you dive, check out Tubattaha.
In Ilocos, check out Vigan. It's a small quaint town with Spanish architecture. Visit Paoay Church as well. And if you surf, you might want to check out Pagudpud in Ilocos Norte.
Baguio is a cute place. Colder temperature compared to the rest of the Philippines but I'm a beach person and I get a little lonely in Baguio maybe because of the temperature. Since you're going to Sagada, you might also want to check out the Butbut tribe of Buscalan Kalinga. You will find the tattoo hunters in the mountains but be sure to have a tour guide. Don't go there by yourselves.
There are also nice beaches that are a 3-hour bus ride from Manila. Go to Zambales and check out Anawangin, Capones, Maskara and the other islands.
Are you from Korea? I'm going to Korea and would appreciate if you could recommend non-touristy destinations too :) you may email me firstname.lastname@example.org. Happy and safe travels!