I wear my navy blazer most often with cream, tan, light grey and medium grey trousers. Depending on the trousers, time of day and my mood, either black or brown shoes. The medium grey trousers are flannel most of the time (I have maybe one medium grey trouser that is not flannel). Shirts almost always in the pink, lilac and light blue range with various patterns mixed in. For whatever reason, I am not a fan of white shirts with a navy blazer and like them better with suits. The tie will (obviously) be something that I think goes well with the shirt. Common examples for me are:
Light Blue Shirt - Silver/grey, burgundy, yellow, green, lilac or pink ties.
Pink Shirt - Burgundy or navy/midnight blue ties.
Lilac Shirt - Navy/midnight blue or silver/grey ties.
I'm sure there are some combinations that I'm overlooking, but that captures a lot of what I'll wear with it.
Today's picture is a double breasted navy blazer with silver buttons by Hemrajani, purple stripe extra slim fit french cuff shirt by Charles Tyrwhitt and silverish grenadine grossa tie by Sam Hober. Not pictured are Barry Bricken medium grey flannel trousers and black Crockett & Jones Drummonds. Sorry for the lack of a fit picture; my cell phone camera seems to be rather limited in its ability to zoom out far enough if I'm holding it out with my arm and I can't get someone to take a picture for me.
Anyways, let's see / hear some of your favorite combinations.