I'm quite sure there is such a scene in the opening of true tears.http://www.youtube.com/watch?v=q9_enSauFuk
The whole initial 20 or so seconds should work, in fact.
You should be also able to find such scenes in the various Da Capo anime, I believe, though it's more of sakura tree flowers rather than actual leaves.
Another scene that could do is in the first of the three Bungaku Shoujo Memoire OVAs, at around 11:18.
If you're fine with odd art, check out Fuyu no Hi, as it has some shorts that could do, the first one in particular (the one after the intro). The short with the frogs could also be useful as well as maybe the one with the art on the black background.
Sticking with odd styles, how about Tatami Galaxy? Episode 5, at 2:55 up to 3:10 or so, though, once again, it's more kinda like sakura flowers rather than actual leaves. Another weird looking show that has such scenes is Windy Tales, at the very least the scene at 00:46 in the opening (though IIRC the DVDs do not have the creditless opening, so that's limiting).
Back to more normal looking things. Episode 1 of Natsume Yujinchou, at about 02:40 and 07:38. These could work decently. 0:56 could work as well though it's kind of a "slow" animation so might be hard to use. Have yet to check the whole show but could potentially have more such scenes.
Mushi-Shi should also have many usable scenes. I think the whole show has such scenes IIRC. Other shows that should have them but I don't quite recall precise scenes are House of Five Leaves, Spice & Wolf, and Kino no Tabi. Also, various Shinkai and Ghibli movies might be worth checking, since there's a lot of scenery porn in those: I think Princess Mononoke and Miyori no Mori had such scenes, but eh... can't quite recall anything quite exactly. Usagi Drop also probably had something, but it could have been flowers, so don't count my word on it. Same feeling with Chihayafuru, but again, even here I'm not quite sure if I just am recalling wrong.
I'll update this post if/when I can think of anything else.