I second the comment by guys. Bryn Mawr is a very well regarded program. But if it isn't what you want, you should spend a year bolstering your application and apply anew to programs you prefer. However, I'm not convinced that the MA Humanities program at chicago is going to enhance your application to Art History programs necessarily -- you may want to consult an advisor you trust about this -- especially because from what I understand you aren't necessarily enabled in that program to work deeply with the Art History department there other than taking a few classes (I could be mistaken). For what it's worth, and apart from the skepticism that accompanies all of the grad cafe and other message board parsing of that program, I do know someone who loved it and felt it helped his application to Comparative Lit programs.
But I'm becoming convinced that Art History departments are quite set apart from other Humanities PhD programs in their particularity about what comprises a strong applicant. Reading through this thread, and knowing my own experience and that of others, it's clear to me that 4.0 gpas, MA degrees, publications, teaching experience, museum/curatorial/archival/archeological/etc. research experience -- all of these together won't ensure acceptance to a choice PhD program, nor that you'll get funding, nor that you'll be admitted to any program at all, necessarily. I think the number of great AH phd programs is sufficiently small (fewer still offer great funding) that those programs can be exceptionally selective about admissions. It appears to me that at the level of comparing top candidates -- far too many for the limited spaces in these programs -- factors like personality, network/connections in the field, and quirky criteria about match with research notions all become key. Just speculation here.