We had our daughter's baptism at the Reading Room of the Filipinas Heritage Library. It's located at the corner of Makati Ave. and Ayala Ave., just in front of Manila Peninsula.
Its just a small venue that's good for small parties, around 100 people or more. It has a very nice ambiance. It even has a gallery for paintings, and a library. The rental of the venue is a little expensive and if you have your party on a holiday, it's double the charge. There is available parking within the premises but there's also an Ayala public parking right beside the venue.
From what I know they also have an outside area for parties with more than 100 people, but this is open air, and it might be difficult if it rains.
I think for small intimate parties, this would definitely be a nice place and very accessible.