Blue coat, black pants or the other way around? Should pants be lighter or darker than the coat? How about pinstripe black sport coat and solid black slacks, a do or a don't? Any advice would be welcomed.
A point of clarification - navy is great with black shoes.
OTHERWISE AVOID BLACK IN SUITING OR ODD JACKETS/TROUSERS.
In suiting, it's unversatile and looks like a poor-man's tux, as best, and like a doof at worst. In shirts, it's so high-contrast that it rarely looks good on anyone. In trousers, it makes you look like a waiter or valet.
Pinstriped odd coats or odd trouser are poor choices, as they always look like orphaned suit pieces.
Never mix two pieces of the same color that aren't 1) from the same manufacturer, and 2) from the same fabric, and 3) from the same dye lot. Otherwise they won't match and you'll just look like you got dressed in the dark.
Black and navy blue do NOT go together, ever. You can only double the black if it is a black suit, which has its place (Leo's esteemed opinion not withstanding! :-P) , but it is definitely rather unoriginal.
Dark coat and dark shirt together is a bad idea, IMHO.
Generally speaking, when you are working with an sport coat and slacks, try to pair them dark/light. That is, dark coat, lighter slacks or vice versa.
Both a black blazer and a navy blazer go well with a nice pair of khaki or British khaki slacks or with gray/charcoal slacks. You can do a light blue dress shirt with the navy jacket, but probably need a white, off-white/tan or ecru shirt. with the black.
LOL... somehow, I KNEW you were going to say that!! ;-)
Not bad, with the exception of the yellow and the red/maroon pants. Just don't seem right to me, but to each their own! Not too crazy about plaids too much on slacks, either, especially in the lighter tones, but that's just a personal prejudice. I do have a pair of dark brown slacks with a light plaid print that I love, though.
I think I like the outfit in the first photo best, though.