Koshimizu Ami, Kadowaki Mai, and Itsuki Yui are off on holiday together, going to a hot spring, etc., and they have set up a "Three Sisters" photo blog of their trip. It looks as if they may be posting a lot of pics, so it might be interesting. They have posted at least once an hour so far. You can follow their trip here.
Amisuke, 21, is one of the top young names in voice-acting. She is Karen in Code Geass and Tenma in School Rumble. Maita (26, in glasses) was Souju in Futakoi Alternative and will be Mimi in Kodomo no Jikan. Yuin (lank, dark hair) was Kira in Futakoi and Moe in Da Capo.
Each of the three has a good blog of their own, as well: Amisuke, Maita, Yuin. But they have set up the "Three Sisters" blog as a separate blog on Yuin's site.
EDIT: It's now the middle of the night in Japan, but they kept posting about a shot an hour up to midnight, including shots of them lounging around in their room in yukatas with one of those wonderful ryoukan meals covering the table.