Hi cruising koalas, and welcome to cruise-chat.com!
I also love dressing up... not just for dinner, but for the evening. As Bernie noted, HAL did away with the semi-formal nights last year, and dress now falls into two categories: formal and smart casual. Even on those smart casual nights (or casual nights on other ships), I still tend to dress more toward the semi-formal.
This sounds like a fascinating cruise. Enjoy!