The dog park idea is an excellent one. If he feels comfortable at the park, it would be a great place to start the process. I think your Dad had good intentions by having your neighbor walk the dog, but it was probably a little too much too fast. Agility classes are also a great idea - it will help build his confidence and make him more comfortable. As far as treat go - make sure they are really good ones (I use little pieces of hot dogs - my dogs just love them) - and have him toss the from a distance away at first and eventually Sesh will start associating your neighbor with yummy treats. Little by litte Sesh will come closer to your neighbor and eventually approach him for the treats.

If that spider you were deathly afraid of wanted you to take a piece of chocolate out of its hand before you got to know him and understand he won't hurt you - would you take it?

Good Luck - it sounds like you are definitely going in the right direction.

ps - sorry about calling Sesh "her"