TREASURE COAST CARDS (aka Jim's)
Sanctioned tournaments every Tuesday and Friday (either draft or Standard).

Jim's is located at 7222 S US Highway 1 in Port St Lucie (intersection with Rio Mar; first light north of Prima Vista).

BIG DOGS THUNDERDOMG GAMING (aka Joel's)
Big Dogs Thunderdome in runs MTG tournaments - sanctioned Standard or Draft on Wednesday nights and periodic unsanctioned "Big Dog Battle Royales" on some Saturdays. Check their schedule for upcoming events (MTG and otherwise)

Big Dog Comics & Big Dog Thunderdome Gaming are located at 4804 and 4806 S US Highway 1 in Fort Pierce (White City area, just north of Midway Road in the plaza next to Dunkin Donuts)

For Warhammer & Warmachine/Hordes, go over to Treasure Coast Wargaming.