Vicky Kennedy would be a good candidate and Senator, and I wouldn't mind her running, but it's disappointing that the Mass DP thinks other candidates wouldn't be likely to do well. Brown may be moderate by national GOP standards (which says more about the latter than the former), but he's definitely to the right of most recent New England Republicans--Snowe, Collins, Shays, N. Johnson, Chafee--except for New Hampshire, and even then, has had their GOP moderate (Sununu replaced Bob Smith, Jeb Bradley replaced Sununu, Gregg has voted more moderate recently).
Of course if what you say is correct in your feelings then there is the possibility that Brown could be helped out by a hard fought Democratic primary.