Haven't been there myself yet, but a couple friends of mine swear by
Kungkungan Bay Resort (KBR).

http://www.kungkungan.com/

I am not sure whether it is too far away from where you are staying,
but I spent 10 days in Walea, Togian islands, central Sulawesi (BTW,
is southern Sulawesi still off-limits because of some sort of
guerrilla rebels?).

It was in August, had been raining (unusually, according to the
residents) for days and viz was quite low, although things changed
after our arrival. Not much of the big stuff, yet I guess that greatly
depended on the low visibility. Great, great macro and corals. Food
was excellent, beautiful island (a large one, with a couple of
fishermen's villages).

The other side of the coin: a bit of a trouble to get there (the only
foreigners we met on our way being mining and oil engineers); very
basic resort (no warm water, though they were planning to introduce
it); quite expensive.

According to those who had stayed in Manado, Walea was way much better
in terms of macro, pristine environment and being just a very small
resort (12 rooms, I guess) out of the world; not pricewise. Let's say
I would go back there, but it is not at the top of my priority list in
that region (I would first return to Layang, Sipadan, Mabul); at the
end of the day, however, I am sure diving would not disappoint you.

Vic