I will through my thoughts in as well.
When I first saw your image, I thought it was great and I still do.
However, when I thought about the overall objective, it is to attract people to the art exhibit.
So one way to get some more direct feeback is share a few versions with potential folks that you are trying to attract to the exhibit and see what catches their eye.
Another angle would be if you have several different marketing channels (e.g. posters or local news, or over internet, you could always have more than one design one each in the different channels as not one image will be appealing to all.
Just some quick thoughts
John Wheeler