How do I maximize on this MONSTER flop, ie when to raise?

[foobar]

Unlike other posters, I don't hate the flat call on the flop, although my reasoning is different than yours. You say you just flat called to keep all 3 players in the pot, which is OK...but you're not likely losing anybody with any kind of draw or reasonably made hand for one more small bet. I think a more valid reason for playing the flop your way is to get more action on the turn/river. A spade comes on the turn and BB leads into you. OK, he's either taking a stab or he got there w/ his flush. I think you need to raise here 100% of the time. Granted that the smooth call flop in multi-way pot, raise the turn looks like a strong hand, but I think you're still getting action from the BB if he made his flush.