It is interesting. I have a friend in the DC area and her son took Lang first and Lit second, too... but at our school mostly juniors take Lit and seniors take Lang. I have no idea why and didn't think to question it.
My son took world history (honors but not AP) as a freshman, then AP US History as a sophomore. As a junior he took AP Lit, AP Psychology, and AP Macro/Microeconomics (one class, but two AP tests). This year, he's got AP Lang, AP Government, AP Physics 1, and AP World History. I think World History is a complete elective... he didn't any more history credits, but he liked the teacher (same teacher who taught Econ.) I don't think he's enjoying world history as much as he expected, but if he passes, he'll be able to count it toward his "world studies" gen ed requirement.
My daughter is a current freshman and she's scheduled for honors (but not AP) bio and chem next year. I don't think it's common for kids to go STRAIGHT into AP sciences here (at least not Bio and Chem). She is considering taking AP Bio and/or AP Chem as a junior or senior, though.
DS told me last night that there was going to be some sort of cookout for the seniors on the parking lot today (he was grumbling because it's the lot where he normally parks that would be closed.) I think he thought it would just be for the lunch periods but apparently it's an all-day thing. Kids brought their dogs, etc. He said so far, only two teachers have held class (they are the two whose AP tests are yet to come). The rest of the classes released the seniors to go outside. I think he had fun... but he said he thinks he's going to come home after his "real classes" are over. The kids still have "senior finals" next Tuesday so the year isn't over, but maybe it sort of is. (DS only has 2 finals, and they're in his semester-long mixed grade electives. His AP classes don't have finals, and his non-AP Calculus teacher said that if you have an A average after the most recent unit test, you're excused from the final... so DS is excused.)