Um, Dave love, when I read your post I had an immediate answer to your question 'When was the last time you were in a restaurant and noticed a single diner?'. Last week. Wednesday. Lunch at McDonalds after we had gotten our passport applications done & needed to feed the boys lunch quick before returning them to school. Young college-age-ish fellow a couple tables over by himself dressed in a shirt & tie doing something with a laptop as he ate. I notice single diners from time to time. I've been tempted to invite them to join my little family just so they'd have someone too but there's that whole random-ax-murderer thing....Lol!
I've been a single diner at WDW only once, at Kona last May the morning I felt too crappy to move on out for the day with my brother & his girls. Instead I slept in & went for a nice meal alone. It was a very odd experience for me just because I am so rarely ever alone, have never lived alone, or anything remotely like it. Lol! Honestly, I think a solo trip somewhere -anywhere- would probably benefit me if for no other reason than to 'push-past' my little comfort zone & feel comfy in my own little person-space.
To the OP, I agree with the tours and dining. Very cool stuff! Have fun and be sure to come back and fix us up with a report of your adventures!