If you are going to get a family boat with young kids involved and inexperienced sailors, I would get one as large and stable as I could afford. The Catalina 30 fits that bill nicely but there are dozens of others.
I would second the caution noted by some about whether this is really a good idea with so many involved and inexperienced and not knowing if they will like it.
Finally...about your question on price. If you saw a 1990 Mercedes at the same price as a 1990 Chevy...what would be your conclusion about the condition of the Mercedes?? You will need a competent SURVEY of any boat you settle on to avoid such issues. Catalina 30's go for significantly more $$ than Catalina 27's in the same condition and age range.