- Kodansha titles include Akiyama Haru's Octave and Shirasawa Marimo's Nobara no Mori no Otome-tachi. Kodansha titles are off the table for Seven Seas because Kodansha has a US publishing branch, Kodansha USA.
- Shueisha titles include Eban Fumi's Blue Friend. Don't ask about Hayate x Blade either, because Seven Seas had to stop publishing it a few years ago because it switched publishers and became a Shueisha title.
- Shogakukan titles include Nakamura Ching's Gunjo, Onozucca Kahori's Aido (a.k.a. Love Slave), and Est Em's ongoing Golondrina. Shueisha and Shogakukan titles are a no-go for Seven Seas because Shueisha and Shogakukan co-own Viz Media. Because Gunjo, Aido, and Golondrina are Ikki magazine titles, if any of them are published in English, it'll almost certainly be under Viz's Ikki line.
I'm sure there's something I missed, but those are all the relevant Kodansha, Shueisha and Shogakukan titles that are on English speaking yuri fans' radars.
I asked the guy representing Kodansha USA at Anime Boston about Octave (I tweeted from the Kodansha USA panel and @angelx03 thought to tweet me to ask about it), and he looked intrigued when I described it and said he would take a look at it, so fingers crossed. (And psst, maybe politely let Kodansha USA know that you're interested in Octave too! Nothing to lose from doing that, right? Here are their Twitter and Facebook accounts.)
Also, awesome, Kisses, Sighs, and Cherry Blossom Pink must be selling well if Seven Seas is asking about which yuri title they should look into licensing next. There are a bunch of titles I would love to see in English, so even if one I voted on isn't chosen, I'll probably still be happy with what they choose next. I cheated and voted for Shimura Takako's Aoi Hana and Morishima Akiko's Hanjuku Joshi. I hold both titles near and dear to my heart.
The reasons for my choosing Aoi Hana are, I hope, obvious. And why Hanjuku Joshi out of all of Morishima's wonderful oeuvre? As a two volume story, not just a series of one-shots, it's probably the best title for them to publish first by Morishima- although I'm not sure how much its sexual content- i.e. the need to shrinkwrap and be like "Don't read this if you're under 18!"- would limit its sales (not that I wouldn't be perfectly fine with being proven wrong), even though I would have loved the hell out of it in high school too. Minamoto Hisanari's Fu~fu would be my next pick. Hayashiya Shizuru's Strawberry Shake Sweet may be a bit too old at this point, much as I love it to pieces too (Tachibana Julia is my hero), and Nishi Uko's Collectors and Yamaji Ebine's yuri titles don't seem like they really fit Seven Seas' catalogue regardless of age, awesome though they are. Takemiya Jin's Omoi no Kakera would, imho, be a great choice for Seven Seas after it ends, since it shouldn't be very long and has growing buzz among English-speaking yuri fans. But again, there are plenty of other titles I'd be happy with too.
So yes- there are a load of titles you can vote for, so vote! You can not only let them know what you want on Twitter, you can let them know on their Facebook page.