I've updated my page with pics of the characters and seiyuus in Hidamari Sketch x365. It now includes not only the four main characters and Yoshinoya-sensei, but also Chika, Natsume, Landlady-san, and Ume-sensei.
Here's a photo of the four main seiyuu, along with the mangaka, Aoki Ume, who plays the little green "Ume-sensei" character (click to enlarge a bit).
(l-r): Gotou Yuuko (Hiro), Mizuhashi Kaori (Miyako), mangaka Aoki Ume (Ume-sensei), Asumi Kana (Yuno), Shintani Ryoko (Sae).
And here's what the page itself looks like:
As for the show itself, I was blown away by episode one: artistic, funny, and touching. I didn't finish the first season, feeling I had got all the show had to give. But my enjoyment has been refreshed by the first episode of the new series.