Since you've been a WB member since 2007, I'm guessing you probably have a few dozen miles of experience at least. So I figure you probably know all you need to know about your own capabilities. Maybe just looking for confirmation from others, or unsure if you've got what it takes to tackle a thru or long section. Chances are, you do. Longest section we've done is 100+ miles (MA,CT,NY) and several in the 70-85 mile range. We regularly manage 10-15 mpd, but distance is often limited by factors other than the energy required to hike that far. Factors like sore feet or a sore back stop us as often as being tired.
From the "we" in your post, I'm guessing you're a husband/wife couple. As with any pair of hiking partners, if you hike together (as opposed to simply meeting up at the end of the day), there are compromises that have to be made. My husband is long-legged. At his normal relaxed pace, he quickly outdistances me - so I walk in front and set the pace. If I have the energy and drive, I like to keep moving whereas he's inclined to stop more often for water, to sit on a log, or take in a view - so I stop with him. When one of us runs out of steam, the other waits patiently. Give and take. From your post, it does sound like your hiking style is pretty laid back. Wish I was retired!