Here are some scans from Leon showing several great examples of how to pair up white pants and sportcoats for summer.  Not too difficult, and the navy blazer matches up great again.

White Pants for Summer - Example 6

White Pants for Summer - Example 1

White Pants for Summer - Example 2

White Pants for Summer - Example 3

White Pants for Summer - Example 4White Pants for Summer - Example 5