My two cents. The combinations suggested and are choosing is the best choice for a formal event. So stick with it
The purple shirt and tie is a good choice to wear with a black suit for non formal events. Yes, there are many people here who will say you look like a clown. But But many people on this forum think you will look like a clown by simply wearing a black suit, if you wear jeans with a sports coat, a sports coat without a tie, a shirt and tie without a jacket. At the same time they think it is o.k. to wear coloured socks with a suit, or to wear a scarf as a fashion accessory. They take their own biased opinions and present them as facts. This is wrong, wrong, wrong! Think they are the owners of good taste. What arrogance! Take their advice with a grain of salt. There I said it and got it off my chest. Out of respect for the other members of this forum, I will not start a flame war, and let them have the last word.
Tie width: If you suit is a modern cut suit with very thin lapels avoid large ties. It will look disproportionate. If you suit lapels are three inches, do not go for ties that are over 3.5 in width.
Again my two cents. Do not go with a black tie. People who do that think that because a black tux, black bow tie work, a black suit, black bow tie will also work. What works for the former is the satin lapels of the tux match the satin fabric of the bow tie. A bow tie also takes up a small space on the chest allowing more contrast between the black tux and white shirt. Secondly, a tie is suppose to stand out. One will not wear a blue/ grey suit, with the exact same shade of a tie, so why black suit black tie? I like Bacnals advice better and would go with a blue tie. I would also make sure the tie is not too dark and matches the shade of the suit.