[illini43]

By checking the flop, you possibly give a chance for a free card. There are a ton of cards you don't want to see on the turn (spade, overcard) - make them pay to see. Also, check-raising will usually only get worse hands to fold and better hands to call/raise. Leading out is optimal here - it will thin the field as much as a c/r would without commiting a big chunk of your stack.