After shooting and processing tens of thousands of photos, I have never needed layers.
Post-processing (tweaking) photos will not involve layers 99% of the time. Photoshop is fantastic (as is PS Elements) for layer-based work, but given the poster's needs, layers don't come into play.
Conversely, I find myself using layers more and more. From dewrinkling portraits to adjusting backgrounds I find that using layers speeds up and provides me with better results overall, even if I'm doing something I used to do without them. If "light touch up" includes fixing skin in portraits, then I'd say with layers I can get acceptable results in under a minute versus about 10-15m without. If "light touch up" is just levels/saturation/contras then Elements is fine if you're sure you're not going to start fixing up faces.