Matrix metering meters 75% across the entire frame, you don't really need to meter at the brightest spot. The metering reading is averaged out, the readings tend to be 'faster' than spot.
Spot metering meters the spot you focus at and calculates the exposure, thus you need to spot meter at the spot you'd like to be correctly exposed, I use this mode mostly when I'm out in the hot sun or covering portraits.
If I'm to shoot ambient and dimly lit area, to get the mode, I'd shoot wide open and use matrix metering instead of spot. Spot only if I have VR, cause that would stabilise my arms but it still won't freeze image. Flash will tend to be a bit harsh in dimly lit areas and might spoil the mood.
Let me get some shots processed and I'll show you how the matrix & spot metering works. I just used matrix for some ambient shots last night and used flash also for church.