I took a Crank Brothers F15 with me on my seven month, 5,300 mile (8,500 km) bike tour. It's a good multi-tool, but like most, it's not very ergonomic, and can at times be quite awkward to use. So I'm thinking that before my next big tour, I'm going to get a set of Fix It Sticks. I would worry a bit about the loose parts getting lost, but it just looks so much nicer to use. Like a proper set of full-sized L hex wrenches, it should fit into tighter spaces, and there aren't any pivoting parts to flop around when putting significant torque on it.

Other than that, I carry two Pedro's tire levers, a Topeak Road Morph G pump, a patch kit, and a spoke wrench similar to this one. I also had a Leatherman with me, which was most often used for the can opener, but the pliers came in handy for a few fixes on the bike, like pulling shards of glass out of flat tires.

I also carry several consumable spare parts and such. A bottle of chain lube, a few spare tubes, one new set of brake pads for each wheel, and a small thing (an old patch kit container) of extra rack/water bottle cage bolts, which has saved my day several times. You should definitely get in the habit of regularly checking over the bike and snugging up any bolts that start to shake themselves loose, but also carry a few extra bolts in case one does fall out. That way you won't have to zip tie your rack back together when the next bike shop is a week away. Oh also, zip ties. Definitely bring a bunch. Even checking the rack bolts regularly, zip ties will still come in handy a lot.