Spring, Summer, Fall and Winter is NSFW, if I remember correctly. Lol.
If you want to introduce someone to yuri, shouldn't a series about girls falling for girls for the first time a good way to start? Like the series Resounding Echo? There's many more, but I can't seem to remember now. sigh
I wonder, though, if it's too much to introduce angsty yuri to non-believers the first time around... -.-'