I do believe that Janna is situational, because she more or less requires an AD carry to do well. Furthermore, it is of advantage if that AD carry is one that needs protection, like, for instance, Vayne. Ezreal and, to some extent, Corki need less babysitting, and thus are less reliant on Janna.
Saying that I main Lulu/Janna is arguable. In either case, I see Janna much less picked, especially since Ezreal is such a common AD carry, and also because Lulu is often better. Also, let's not forget that non-standard "supports" can also protect an AD carry fairly well, such as Leona or Blitzcrank.
I usually/never troll forum posts, though. I tend not to troll the NA chats either.
Anyway. A Janna spotlight wouldn't be bad either, but Janna is a fairly complex champion. Her skill ceiling is high, so it'd probably be best if some veteran Janna player provided the video material. Janna might not be that viable in lower elos of play, due to the lack of good AD carries to protect. AP Janna got nerfed too much to be a very good pick, in my opinion. It can probably still work, but it's less rewarding than before.
I still see Corki much more than I see Janna in current tournament play, though, at least in EUW.
Sona is not really used much in EUW, though the recent skin increased her usage a bit. Anyway, I guess this is a bit off-topic. I blame DiscworldDeath for that*. ^_^
*Oh, I guess that part is trolling. Hah. :P