Hey flounder, welcome to touring!
source for racks, panniers and excellent personal advice about them:
www.thetouringstore.comthis is one guy, Wayne, who is a major distributor for the US for a couple of good brands of touring gear. You won't go wrong buying anything he carries, and he can help you make decisions. (no i'm not a shill)
There are a lot of gear lists on
www.crazyguyonabike.com, you could look at some of those for ideas. Most people take a bit too much to start with, but it's easy (if you live in the states) to mail stuff home that you're not using.
I really rather dislike my Arkel panniers because they are very heavy. Other than that they are nice. The first thing to decide is top- vs side-loading, and do you need waterproof. I like side loading b/c you can get into your bags even if(when) you have stuff loaded on top of the rack. Other's like top loading for their one-big-pocket simplicity, and they can be waterproof (there are no waterproof material side loaders). If your bags aren't waterproof you need to either have bags inside (can be fancy like Arkels or simple like trashbags/ziplocks) - or outside, like rain covers. If i had it to do over again I would probably buy Lone Peaks.
I personally would not go with a 3 person tent, I would take at least 2 tents, in case you separate along the way (for the whole ride or just a few days) and also you should think about whether that's enough personal space for you for a long trip. Maybe you are a family and know it's ok, but otherwise... i would take 2 or 3 tents, anything under 5 pounds for a 2 person tent is reasonable, closer to 4 is easy to get w/o being ridiculously expensive.
rei-outlet.com is your friend.
have fun with the planning and touring!