Suggestions for improving class dynamic

[glover]

I'm an experienced Esl teacher , but always learning. Right now I am teaching a group of 8 high intermediates (well, one, the only male in the group, is lower). 4 of the 7 women are here in an au pair program that requires their presence in an Esl class. All the women are bright, lively, and communicative. That's mostly good news. But lately I've felt they're no longer motivated. They don't seem to take the class very seriously and see it more as a social 2 1/2 hours. I'm glad they've all bonded so well, but am starting to get annoyed with the extent of side/off topic conversations, unnecessary checking of cell phones, lateness back from breaks, etc. I work hard at providing lots of s to s activities And at keeping the class interesting, but many of this group fly thru assignments quickly and seem to bore easily. And those seem to influence the others in a similar direction. I acknowledge that promoting lots of student interaction, while still ensuring a good learning environment for all, always been my greatest challenge. I came home frustrated and discouraged last night. I'm torn between thinking I'm not being "firm" enough and/or not engaging them well enough. Suggestions?