... If you have this cleared go/drive with your wife to a big & good brick and mortar outdoor store, let her choose what she likes from quality manufacturers, have it properly adjusted by the personal, loaded up with aprox. the maximal intended load and carry it at least 15 better 30 minutes...
REI, even small one, are especially good at this. Good selection of brands, and a bunch of weighted bags for loading. Others are hit and miss on how helpful.
If technical stuff, bring it. When I got my last computer/camera/etc. bag I brought my current one and loaded up the various bags, several times, before we settled on one. I was in the Chrome store doing this for over 2 hours. But 5 years later I have the bag still.