You mean at the beach minus the dogs? If so, I'm not crazy about it in that setting. I love it for bar hopping, but it feels almost formal (?) for hanging out at the beach. I think you look adorable in it, but it doesn't necessarily say, "beachy good time" to me. Maybe something lighter (in fabric, not necessarily color)?
If it's light and airy, it's fine. The lighting makes it look like a heavy fabric, but a light fabric will help alleviate sand stickage if there is any playing in the sand . I'd wear some sort of flat (or wedge, since it's flat when it hits the ground) or teensy heel if you're going to be walking in the sand; we don't want the sand to suck in your heel and make you fall down! No second date injuries!
They are both cute dresses! The black could be jazzed up with fun jewelry! Although the green dress would be fantastic with some silver jewelry, too. You can't really go wrong with either!
If it was me, I'd wear nude wedges or some black dressy flip flops. I live at the beach as you know, so that is the type of stuff I wear all the time. Do you have either option? Post pics! Oh, and more dogs too.
I'm probably too late, but it would help to know which beach area you will be bar hopping at. Either one of those dresses would be too dressy for beach bar hopping in the South Bay (Hermosa, Redondo, Manhattan). We were down there this morning and it was very jean shorts or board shorts with tank tops and bikini tops under them. And flip flops. And a surprising number of red, white and blue hair accessories!