I'd like to update a walnut stained triple dresser

It's a bit of work to lighten dark wood. Usually it's done with bleach, but you might want to lightly sand an inconspicuous spot and see how much lighter the piece might be just sanded. Wood naturally grows darker over time and you might be surprised that a bit of sanding might accomplish your goal.

http://antiquerestorers.com/Articles/SAL/Bleach.htm

You could also try stripping the finish with Citristrip. Years of use and darkening of the original finish could be erased with a good stripping.

Knicks and scratches can sometimes be "fixed" with sanding, but you can try wetting the areas and letting the grain of the wood fill in the knicks and scratches. If they are too deep, try using a wood filler.

If this is a walnut wood, it does get darker as it ages and bleaching may do nothing to lighten it. I did have a walnut table that looked so much better when it was stripped and sanded and treated to a new finish.

I did this to a dark desk. I kept the dark top, but then used Martha Stewart beadboard wallpaper around the bottom. I then painted the wallpaper a light cream (just a tad darker than the white wallpaper). I LOVE it!

Back in the eighties, the house we lived in had very dark kitchen cabinets, partly just darkened from age. It made the kitchen real dark and it wasn't a very big kitchen. We stripped the doors first because they were the easiest to get down. When we striped them, the color left was so great that we just cleaned them up and put on finishing layers of polyurethane, we didn't restain them at all. We were very happy with the outcome when we finished them all and had everything put back together.