If you're going Goliath Druid, I recommend building into the (somewhat ridiculous) Vital Strike build. Since at 12th you'll be Huge in size, why not go ahead and make your one giant smash each round even more giant. With an Impact weapon and a 1-level dip into Titan Fighter or 3-level dip into Titan Mauler Barbarian, you can cap out weapon size. Shaping Focus lets you not lose progression in Wild Shape while dipping levels. Just build out all the things that make your giant smash go.
The build is alright through 11th level. Play it like a damage dealer, not so much like a tank. You'll have some Con, but kinda bad AC. Not that anything wants to stand in to test you on it. BUT... at 12th level, you'll become a nigh immortal character essentially immune to hit point damage, thanks to the combination of Regeneration from your form and Ferocity from something like Juggernaut's Pauldrons. Can't be knocked out for being below 1 HP, can't die either. Woof.