It all depends on whether they are all selling the same thing to the same persona. If yes, then combine all the campaigns into one adwords account, which feeds into one analytics account. That way they can get feedback on the effectiveness of different keywords, ads, etc. more quickly (because there will be more data, from all the different websites, all in one place, for a particular keyword).

If they are each selling different things, or to different personas, then don't combine their accounts, because it will just make things confusing and not useful from an analysis perspective.