Create a membership site

Design and build a membership site around a specific idea for our business >members will be in one 'tribe' in the site >we should be able to post challenges, articles, journal posts, etc. for the members w/i the site >we should be able to email these prompts to members >we should be able to post on social media to drive traffic to members >members should be able to interact in the site >we want to have a place in the site where we can post related articles in each tribe >possibly there is also an overall general area where anyone from any 'tribe' could go where perhaps thee are 'best' content from members, as well as articles, etc. -- if this is possible The flow: Members login, get into their tribe, see weekly prompts, post on prompts, read and interact with others. There should also be sections for articles, etc. to be uploaded (like a blog platform). This is a concept we like (which isn't a member site, but would have similar content): [login to view URL] We don't mind it being built/customized on an existing platform (ex Ning, etc.) if it can do what we need, and look ) but some existing platforms (Mightybell don't seem to be able to do all we want). So may need to be a combo of out of the box + customization. Therefore we are looking at someone with knowledge of which Membership platform sites are out there, are familiar with their functionality, etc. For example; could we use Kajabi, or ONTRAport? We want: -- a streamlined UX -- Clean design -- drive members to the site from social media and email