Well, of course, you have to make MANY trips on Buzz Lightyear's Astro Orbitor. Also, you will HAVE to eat at Pizza Planet at Disney MGM. And you can't leave without visiting All Star Movies to see the Toy Story building. In fact, you could always STAY at All Star Movies in the Toy Story building!
Buzz can usually be found for autographs by the Timekeeper Entrance to your right hand side as you enter Tomorrowland from Main Street USA.
Woody, Jessie and sometimes Buzz may be found near Pizza Planet at Al's Toy Barn.
At Downtown Disney, there is a lifesized statue of Buzz outside of the Once Upon a Toy Store. Kids love to pose for pictures with him there. Mr Potato Head (statue) is there, as well.
If you want to know where Buzz is scheduled to be for the day at a particular park, drop by Guest Relations and they can find out for you. Remember, this is when he is SCHEDULED to be there... but you know... he may have to go and fight Zurg which could occasionally hold him up... so if you don't see him at his scheduled time and place, he is probably out saving the Universe!