I'm not one that will enjoy a TS meal alone. I think that's my biggest issue.
I was worried about this too but didn't have any awkward or bored moments eating alone. I always had park maps and my itinerary to look over, I used the time to text my friends and post facebook updates and most of the time I spent talking to the servers, people watching, or taking in the scenery.
My favorite TS was 50's primetime cafe, I spent the whole time either talking with my waiter or watching the waiters mess with other tables. I was so busy laughing I never had a change to look at my map let alone get bored. I was worried about eating here solo since they mess with people but even when my waiter used a kazoo to make plane noises while feeding me my green beans I was to busy cracking up to worry about being alone.
I loved Liberty Tree Tavern also, not only was the food great but they sat me at a two top in a bay window and even though the glass was the old wrinkle glass I was still able to people watch outside.
I also had amazing dinners at Yak and Yeti (also a window seat
) and at Kona at the Polynesian which had a bit of a wait for my steak but I just used the time to catch up on some emails.
The ADR I was most worried about was Biergarten and being seated with strangers. I sat with a table of 5 ladies (on a girls only trip) and a mother and adult son. The ladies were all talkative and the son was a great storyteller, his mom was a bit odd but 6 out of 7 isn't bad. It was a bit awkward at first but we quickly started talking about where we were from and what everyone's plans were and it ended up being a great time. A lot of the time the band was doing their show so even if I didn't have fun table mates I think it would still be enjoyable.
I'd never eaten alone in a sit down restaurant prior to WDW but am glad i made ADR's, I had some great meals, met some nice people, and my feet needed the recovery time.