Those shirts all look fine (except #4 imo, risks looking dated after a while and you generally want engagement pictures to be timeless) but it's hard to say how well they will work for you without knowing what you look like. Your complexion and contrast will be played up or played down by certain colors, and if you're getting black and white pictures done, different colors also translate to different strengths of gray tones. A general underlying rule of portrait photography is that the clothes should never overpower the face.
Also, when you are not the only person in the picture (which is usually the case in engagement sessions, right?) then you have the additional issue of what will the other person be wearing. You need to be complementary without being matchy-matchy, and neither should overpower the other.
It's a little complicated with so many variables, and it's one of the things stylists and wardrobe specialists are paid to take care of on high-end shoots. In your case, I wouldn't go around buying new clothes just for the session unless all your current clothes are garbage, and don't bring just one set of clothes.
Ultimately, the best person to consult with would be your photographer. A good and experienced one will be able to size you and your SO up and tell you what will work and what won't.
Edited by hyt123 - 4/16/12 at 7:54am