I think you commute is long enough that you could benefit from clipless pedals, particularly if you have any hills you climb. They are more efficient, particularly when climbing.
Since you seem to want to use your bike for short rides to the store, etc, you might consider a combo pedal with clipless on one side and platform on the other, giving you flexibility. Lots of options for this on Amazon.
There are a number of "commuter" or "urban" bike shoes that accept SPD cleats in them. The look like normal casual shoes and the cleats are recessed for walking.
I have a set that I use when I want to walk around more comfortably on stops on a ride. - they basically look like a trail running shoe or light hiker, but have an SPD cleat in them - I think mine are Shimanno, but many brands make similar. I think brands like Chrome make some more stylish/trendy options. Haven't looked on Amazon but sure there are some options.