Well, I think "implement expertise" is pretty much a must-have feat, so I need to pick one asap.
Retraining says you don't -have- to pick one asap, you just retrain into the one you have.
But yeah, your first feat doesn't have to be Imp Ex. You hit often enough in the early levels that you really don't need the +1 to hit as much as you might need other utility feats that help you in other ways. You'll want it by level 15 of course, but before then it's not -that- important.
Earthfall totem is -very- nice for those druids who specialize in push/slide/prone powers (and it's a surprisingly deep pool). If you're into those, through Beast Form or what have you, it's better for damage than Staff of Ruin is.
Razor Talon totem is also another option for Beast Form druids to enjoy.
Totem of Thunder's Keeper is a good control option, giving a push when they attack a friend.
On the other hand, Staff of Ruin is great, and Staff of Thunderwave is probably one of the best dailies for damage in items -bar none.-
Druids can really go so many different ways. I guess the best advice is to see what powers you're taking, and go with the implement that best works towards your playstyle. What works for one guy might not work for you. There's no singular 'best' implement for druids... you can take whatever it is you like.