Having the same domain as the communities isn't good. Each of these different portals needs the ability to choose an independent custom domain. Affiliate portal, communities, members, client portal, and so on, all need their own.

For example the domain used for a website selling products and services may have a client portal attached to that specific site for clients who use that specific site. Rather than one main client portal for all of your sites.

Affiliates would have an affiliate portal domain of it's own for each different site that could be the same as the client portal domain for that site. (But not one main domain for all sites).

Groups/communities need to each have their own custom domain specific to each group preferably and mayne also the option for a unique main domain for all of them if someone wanted to do it that way.

Members area needs to be its own custom domain, possibly even with the option of having a members area for each site built instead of one main members area for all sites. This could potentially be the same as client portal and affiliate portal. As long as it was on a site by site bases not one main one for the whole account.