Business trips are another occasion to dress well. Suit -vs- Blazer
Pack a suit if you are going to have a formal meeting, a blazer if you'll be attending an informal event. A blue or black blazer is the most versatile and will work well for most occasions.
Shirt
Depending on the length of your trip, you may want to pack on or two dress shirts. A white shirt will go with just about anything and can be dressed up or down. A second shirt might be useful to give you a different look. You may want this one to be blue, and of course multiple ties are in order.
Shoes
Black shoes can go along way. They can be worn with either a suit and depending on the style a pair of jeans.
Jeans, Pants or Trousers
An extra pair of jeans, pants or trousers is usually a good thing. A pair of dark jeans, with no holes or fancy pockets will usually get you through. A white shirt with jeans, with or without blazer, will always look sharp at an informal occasion.
An extra pair of pants is always a good idea to mix and match with your suit jacket or blazer.
Accessories
Naturally, don't forget the belt, watch, cuff links, if wearing cuff shirts, and sunglasses. Then there is the normal stuff like tooth brush, tooth paste, deodorant, extra undies, and the like.
