I don't care if there are 14 lanes and you are the only car on the road. You should be in the far right lane. If there is another car, you should still be in the far right lane unless you are passing the car, in which case you should be in the lane just left of the far right lane. There is no "cruising lane" like the lazy people who assume the middle lane is for people just going along their merry way. Here's a hint. If you are getting passed on the right, YOU are in the wrong, not the overtaking vehicle.
In Australia the rule for any highway with a speed limit 80kph (~50mph) or faster is "keep left unless overtaking" (we drive on the left over here), although that rule is removed if traffic in all lanes is congested. Sometimes we have a "slow vehicles use left lane" on a steep climb so the trucks can sit left while they struggle up the hills.
Most people will try and avoid the left lane on multi-lane freeway's though, despite the above rule. Cars will exit and enter from the left so it makes good sense to keep out of that lane so incoming traffic can merge more easily. Also our freeways tend to add and remove the left lane quite frequently - "left lane ending" is a common sign to see, so keeping in the second-from-the-left lane is a good strategy (unless there are only two lanes so nobody can go around you to the right - then it's a stupid strategy). You get the odd tosser who does a lane change a minute, but most of the time they don't get in anyone's way, and don't usually have a hissy fit when someone is in the "wrong" lane. Myself, I just set the speed limiter to the posted speed and (mostly) focus on what's in front. If you get boxed in behind me for a few km then you are going to arrive at your destination a few seconds later - if that causes you stress then you might need to work on that - i'm not going to try and squeeze into that tiny gap on the left just for you. If the road is all clear though you won't be stuck behind me because i will be in one of the left lanes so you can easily go around.
I do remember getting very frustrated one night on the way home behind a car who decided to just sit in the right lane with nothing else on the road apart from the car we'd just overtaken. I flashed my lights, beeped my horn, nothing. My reaction surprised me because stuff like that doesn't normally bother me. I felt like overtaking on the left, moving into the right, and slamming on the brakes. I didn't though. I overtook on the left and went on my way, and told myself to keep my cool a little better next time.