I've been thinking about middle names a lot recently. For some reason -- and this is borderline inexplicable -- it's really important to me that I end up with two middle names, just like I have now (First Middle Mom's Surname Dad's Surname). Instead of picking names that start with the same letter, I've really tried to preserve cadence instead.
I considered moving my birth name to the middle, as it's one of those technically-unisex-but-never-used-for-dudes-these-days names, but the flow is awful with Cameron. Today, while I was driving, I decided that if/when I come out to my parents, I'll ask my father to pick. Of course, that means I'll probably end up with Bruce in the middle. Definitely not the sexiest name I've ever heard, but it seems to be the family name of choice on his side. Or maybe I'll ask my mom and go for something super Iranian, like my current middle name. Ugh, see, even just talking about this has got me going back and forth.

For you, honestly, if it won't grate on you to be called Ian Marie, I do think it sounds nice. I'd like it less if you hadn't said the thing about your dad. I think that makes it sort of cool, having a bonding point over the girly middle name thing, boy named Sue style.