I use wire on my chain necklaces.  You can order gold-fllled or silver, and I'm sure there is base metal, but I don't use that. I also order 14k and 10k for some projects, but you want to be sure with that.  I like 26 or 24 gauge dead soft because it is easy to use.  I use 22 gauge (I think) to create the ehancer/charm rings that I have been making.  When I did my really long tin-cups, I did a loop through the chain and did not finish the actual wrapping until it was all together the way I wanted it.  Does that make sense?  I usually get the wire by the foot, or by the troy ounce depending on who I order it for (something else to Hui on?).  You can get it on the spool, but I've never ordered that much.  If you get a kink in it, (not often) you use a Sunshine cloth to straighten it.  You have to remember that the wire gets harder the more you work it.  Anyone else with advice?  I don't use jump rings for earrings, I use wire, even with the chain.  I also use wire to put clasps on chains.  Here is the long tin cup chain (I need to reshoot that, the pearl colors are way better than those pics).  I use beads to frame my pearls and to give it a more finished look.