Honestly don't get to caught up in the rankings, they are pretty much B.S. look to how the formula works and you will see it makes no sense and the ABA and LSAC specifically say to ignore it. I am sure American is a fine school and if you want to be a lawyer in D.C. it will give you a great opportunity to do that.
Do not listen to people dogging schools on this website either, they are full of s*it. I am sure someone out there did have a bad experience at American and even one of my professors hated Harvard and transferred to UCLA. Harvard is certainly not a bad law school, just because they didn't like it. Your law school experience is based on you what you make of it. It sounds like your goal is to be a lawyer in D.C. and the best way to do that is to go to law school in D.C. Simple as that.
I think the real reason people complain about law school in general, is because they have unrealistic expectations that getting a J.D. will result in having the red carpet rolled out for them and result in having 100,000 a year offers as they walk off stage at graduation and that is just not realistic. Maybe Harvard, Yale, grads have that luxury, but even some of them don't pass the bar and they probably are out of luck finding a job as an attorney, until they pass.
I just remember being caught up in the rankings this time last year and I am so glad I choose not to pay attention to them. My tier 4 school has worked out fine for me and I have a good 1L summer job lined up and did well academically. I am sure American will open plenty of doors for you, but as with any type of schooling it is up to you what you make of it.