I know nothing about SPD pedals. I only ride on flats. Currently experimenting with toe-clips to prevent slips in the wet.Had no problems with the saddle yet but it's only 7 miles to work so at that distance I won't find out. The seatpost has suspension so that would help too.
Something I feel I do need to change are the pedals. I use SPDs on my road bike so I don't want to get used riding the touring bike without them because I may forget when on road bike but I have found that sometimes I have to keep taking feet off pedals a lot especially when off-road so I am getting one-sided SPD pedals such as Shimano M324s and cycling shoes with grips for flat pedal riding such as O'Neal Flow SPD shoes
As for the commute, well, now you have the chance to try out lots of different things such as GPS apps on your phone, a little creative route planning with different resources, maybe trying out different surfaces if that's an option. A 7 mile trip to work can easily become a 25 mile trip on the way home with lots of time to test different scenarios and bike handling.
I've found the positioning of the saddle can be as important as the saddle itself. And that can take a lot of tiny adjustments to get just right.