who should have the last say - the monther or the father?

Actually what you are practicing, making decisions and discussing its pros and cons between the two of you, is really great. You should work as couple and work on one goal, primarily that would be your family. Sometimes though, other partners are less adept when it comes to decision-making so one usually dominates the process and the other is just as happy that all he/she does is nod in approval. But in the case where both are really active in discussing issues and making decisions based on the discussions made. It is not really a matter of who should have the last say. For me, any of you two could have the last say but the important thing there is that you have agreed and compromised some ideas just to come up with a decision. What you have decided is no longer his or her idea but it is now both yours. This is very important so that in the end one would not blame the other. It is both of you who decided so it should be both of you who shall take responsibility if anything goes wrong. If all goes well, both of you gets credit. Fair deal, ain't it?