Any professional clothier will tell you there are five basic sportcoats that everyone should have:
A navy blazer with blazer buttons. This is used for the most formal of your business casual events, i.e. dinner with that major account at the club etc ...
Tan camel hair or cashmere blazer for the fall/winter, as well as its equivalent in the summer, a tan plain weave or linen blazer.
Black blazer with a contrasting brown crushed horn button, or antique silver/pewter buttons. This is a great garment to travel with, as it does everything. You can wear it with everything from blue jeans to a nice pair of wool trousers and a silk shirt or a shirt and tie.
An earthtone houndstooth or glen plaid, your choice. This can be worn with a variety of tans, olives, and taupe colored trousers.
A black and white houndstooth, Prince O' Wales glen plaid or herringbone, your choice. Wear it with black or grey trousers.