Do some research. Sometimes you can manage to talk yourself (or find) a pretty good deal on a "set" vs. just one machine. Generally speaking, if one works fine, then I wouldn't replace it. However, in your case, you are talking about a washing machine that is 14 years old. Pretty much anything you buy "should" be more efficient. Certainly if you get a front loader it will use much less water. But there are other considerations... most machines today are also jam packed with electronics that were absent on older machines. So no worries about a lightning storm frying the control panel on your washing machine. Today---most of them have electronic rather than mechanical controls. So it is something to consider. I was warned to unplug my machine in lightning storms (ever seen a 4 prong surge protector ? me either, lol). Well, we get lots of those where we live, and I have never unplugged it. Never had a problem with it. But for the first 2 years I 'worried' about it every time we had a storm (every afternoon in the summer practically). I mean... what if you aren't even home, ya know?
So if that sort of thing would bother you, (worrying over a potentially fried electrical panel and expensive non-warranty repair), and you can't find or negotiate a super deal on a "set", then I probably would just wait it out and continue to use the washer you have.
If it were the reverse, and your washer died and you were looking at dryer replacement as the "optional" piece, then I would go for it for sure, because the technology (moisture sensors and the like) is far advanced over 14 years ago and they are more energy efficient. Well, as energy efficient as a clothes dryer can be--which isn't that efficient, lol.
Shop Sears and price compare brands. Some stores also price match with a % less to "beat" the competitor---so shop around and always ask if it is their best deal.