that sounds like a really tough choice. i would vote go senator because it probably has a little more wrist presence than the mut without making a ruckus. it would be a little heftier than the mut, and the plain indices are just ever so slightly more elegant in my opinion. the portuguese seems like the odd one in this trio. it's very beautiful but a little too loud compared to these two, and it look big in a way that the go wouldn't. can i get away with saying that it's somewhat less elegant/dressy than the go and the mut? i love the iwc, but it just lacks the panache that the other two have. so i don't think it's quite in the same line up.
i don't own any of these, so you know that i have no direct experience. but what a good son-in-law you are. classy gift.
chris