I guess everyone is different.
I was speaking to my soon to be MIL the other day and even she was surprised at how involved her son wants to be, and thought he would be happy for me to do the planning. Her advice was "be clever and let him feel he's making decisions!" lol
When I told her about the guys suits and how he said he'll take care of it, she said that he'll come to me for advice soon and again just to let him think he's the one who decided. So I'll continue to do my research and when he doesn't know what to do or needs my opinion, I'll be ready