I'm not sure what support those other sites have for allowing multiple people share to one place, but I have used Shutterfly for a couple of years, and it works really well for that purpose.
You just set up the site (very simple), and then "invite" people via their email address. Each person then has their own login to the site, and you can secure it so that only members can see the contents. Everyone can post pictures, tag them, etc., plus you can have calendar events, messages and more that makes it more of a full "site" vs. just photo sharing. The is a free service, so by default Shutterfly will send out periodic emails, but you can opt out of that. Of course, they make money by selling prints, books, etc., but there is no obligation to purchase anything.
This link is where you can start or look into it. I have no vested interest in Shutterfly, except for being a satisfied customer.
Kurt