Not Hurt Feelings vs. Not People-Please


My husband and I met this couple on Labor Day weekend and my husband would like to form a relationship with the husband so he will donate money to some cause.
He asked me to keep company for the wife that day and I ended up sitting with her for four hours. At the end of that day I told my husband that I am not interested in forming a friendship with the wife, and that while I don’t mind going out with them both another time, I would like him to understand my position.
He got a peek into her attitude and behavior and understood that she is not for me, so to speak, but said that she might ask me to hang out, go do things together and so on.
I said it’s not a problem if she asks and that I will simply decline.
Where we differ is as to how to respond.
Of course I will not tell her I am not interested in being her friend, but I also don’t want to people-please and keep giving new excuses each week.

She asked me whether I want to spend few hours next week and go shopping.
I told her I don’t like going shopping.
She then asked me if I wanted to spend few hours going to a brunch and spend then a day at the spa and I told her I have a work deadline and I can’t.

Without hurting her feelings but without pleasing her, how do I let her know that I am not interested in her offers to spend time together?