SplatNZ offers some good advice. Manila is ok - something to experience and is different from the other cities you mentioned.

I haven't stayed at the InterCon but it is near the others and heard it is reasonable.
They are in walking distance of a large shopping centre that has heaps of restaurants and bars where you are sure to find a few that suit you.
Taxis are cheap, food and drink is cheap and services is generally great.

There are a few other major shopping centres that are good for a look also.
There are some sites of interest (am thinking the old Fort, but a google will bring them up), plus the American War Cemetary is worth a visit.

There is alot of poverty in Manila and also some very rich people, so sometimes the contrast is confronting.

All-in-all, I would recommend the visit.