I'm not a fan of Jakarta's bus rapid transit system - called Transjakarta - but for a non-resident, it's ok. It stops by both MONAS (the national monument in the middle of the largest "park" in the city) and the national museum. In fact, they are at located at the same bus stop (called Monas); MONAS is to the east of the stop, the museum, to the west.

If you choose to head downtown, what would you want to see/eat/do? (There are more "tourist" sites than people let on, but getting to or fro them will undoubtedly involve traffic.)