You can successfully use silver and silver-plated wire to make jewelry that you already know will look gorgeous when oxidized. And trust me, it will! I frequently oxidize jewelry I make with this wire, because I find them more beautiful this way. Oxidizing and then polishing the high points give the pieces a depth you don't get on shiny pieces.
If you do not especially enjoy the oxidized look and its patina over time, you should choose non-tarnish silver plated wire.
The non-tarnish silver plated wire will keep its shine for a long, long time. It may get a light yellow cast after long exposure to daylight/sunlight. This occurs because the silver-plated wire has a copper core, then the silver plating, and then an extra, transparent plating for protection. This last layer will eventually change its color, little by little, into a light yellow one, but will mainly keep its silver tone over all. Go with it if you love silver tone jewelry!
I strongly recommend keeping both regular and non-tarnish silver plated wire in sealed plastic bags, separate from each other, away from sunlight - a closet, for instance. This way you're sure to always have your wires as looking new, all the time.
Jewelry should be stored the same way: put them in zip lock plastic bags and then store them in boxes, away from daylight and humidity. A silica gel packet will help a lot if you happen to have some. Every time you take your jewelry off, store it this way and it'll look like new for a long time.