Silver plated necklaces suit anyone who wants that cool, bright shine without committing solid silver money to it, and who's happy to treat it as a two or three year piece rather than something to pass down. If you've got skin that turns every bit of cheap metal a faint green by lunchtime, or you sweat a lot and don't fancy wiping a chain down every night, I'd think twice, or at least go in with your eyes open about what plating actually means.
If you've got none and you're starting from scratch, go for a simple chain with a decent clasp rather than anything with stones or dangling charms, because the plain ones hide wear far better and you'll actually reach for them. Mine gets worn most days for about eight months before the shine starts going a bit flat and honest, usually right where it sits against a scarf or a coat collar, and that's just the plating doing what plating does, thinning out with friction. It's not a fault, it's the deal you made when you didn't pay for solid. What stretches that out is boring but it works: take it off before you shower, before bed, before you put perfume or hairspray anywhere near your neck, and keep it in a little pouch or box rather than loose in a drawer with your earrings, because metal on metal is what scratches the coating off fastest. A soft cloth wipe now and then is enough, no polish, no water.
On colour and finish, the classic bright white silver tone is the easiest thing to live with, it goes with everything and shows the least when it starts to wear because you're not fighting a coating against a different base colour underneath. Anything with a rose gold or yellow gold plating over a silver base tends to show its age faster, because when it thins you get an obvious two tone patchy look rather than a gentle dulling, and I've got one like that sat in a drawer looking like it's been in a scrap. Matte or brushed finishes also hide the early wear better than high polish, which shows every tiny scuff under decent light. A chunkier chain link wears more evenly too, there's just more surface for the shine to sit across.
Next time you're looking at one, check the clasp before anything else, give it a proper open and close a few times, because a stiff or flimsy clasp will lose your necklace in a bag long before the plating ever lets you down.