Just my 2 cents as a Filipino :

Boracay is pretty run down now and overcrowded. If you want something similar, El Nido and Coron both in Palawan are both great alternatives. Less crowded and more "exotic".

I've lived in Manila for a bit, and I have to say it's not that great. It's full of smoke and chaos. The malls like the Mall of Asia and Glorietta are fantastic though. But if you still insist on going, then a few days might be okay. You have Makati and Fort Bonifacio which you can check out.