Fresh f-air is good for off stage kills (Though I've been mixing in bacon spikes) and on stage if spaced right. Down smash is the fastest (Well, after bucket if I believe, but not everyone has something that can be absorbed and it could be weak) F-smash in my opinion is the most versatile, coming out at good speed, and great for punishing spot dodges and rolls (much like many of his moves). Up smash is the slowest as we know, but it's also the strongest, killing at stupidly low percentages, though you sort of have to time this one due to the start up (which isn't that bad if uncharged). Also remember Up smash has IASA, so if you do miss, you can shield, do another smash, or my favorite, down tilt.
Take this all with a grain of salt, I'm hardly a good G&W.
EDIT: It turns out this guy's banned. :v