The moment navy trousers clicked for me was with a cream jumper, flat loafers and absolutely nothing else going on, no statement bag, no clever jewellery. Black would have looked like I was off to a meeting I hadn't dressed for, but navy sat there quietly doing something warmer and less severe, and I realised I'd spent years defaulting to black purely out of habit, not because it was ever the better choice.
They're not the answer to everything, mind. On anyone wanting real contrast, a proper graphic moment where the trouser is meant to be the loud part of the outfit, navy just won't give you that, it reads as a slightly softer neutral rather than a statement, so if you're after drama you want colour or a stronger shape instead. Before you buy, check the fabric weight against what you'll actually do in them, a lot of the cheaper navy trousers are a thin, slightly shiny polyester blend that catches the light in a way that makes the whole leg look flat and a bit school uniform, where a heavier cotton or wool blend holds its shape at the knee and the fall of the leg looks considered rather than limp. Check the dye too, properly, under a window if you can, because navy is the colour most likely to drift toward black or toward a weird inky purple depending on the batch, and you want to know that before you're stood in a cubicle holding it up against a top you thought would be a match. Pocket depth is worth a hand in there as well, cheaper ones are often decorative or barely there, which matters more than you'd expect once you're relying on them for a phone and keys. As for what to avoid, steer clear of pairing navy with black, it's a pairing that looks like an accident rather than a decision, the two reading as a badly matched version of the same colour rather than two colours doing a job together. Navy next to brown shoes works far better than people assume, but navy next to a cooler grey can go a bit flat and corporate, so I'd rather reach for cream, burgundy or a warm tan to sit alongside it.
A cheap pair will get you through a season before the knees bag and the hem starts to fray at the heel strike, a better pair, properly cut through the thigh with some structure in the fabric, will still be hanging properly after three years of actual wearing, not just sitting in a wardrobe looking neat.
Try them on with the shoes you'll actually wear, flat shoes change where a hem should sit far more than most people expect.
