I didn't know this, I thought you only got one tour as a Tesla owner, I didn't know you could go multiple times. So each year you can request another tour?
My first Factory Tour was 2014, then 2016, then again in 2017.
Only two more factory tours, and I get a Jacket. (jk)
Each tour time, there are more areas revealed and then to (visually) learn and discover.
First tour was overwhelming: lots of product (glass for windows, racks of stamped metal, seats, etc.) stored inside, major portions of the old factory needed to be "Freshened Up", somewhat constrained assembly line (figure-8 configuration!). Lots of employee/workers on bicycles inside the plant. We were allowed to walk amongst two Roadsters (one was only a model) and three early versions of Model S at end of tour.
2016 Factory Tour, just prior to Gigafactory opening party: A Mini-United Nations assemblage of tour participants: Germany, Australia, Finland, England, Russia, maybe France (?), Canada, etc. Even a Model S owner I know from DFW was there with her family (unplanned meeting--serendipity). Major portions of the factory have been completely repainted and refurbished. Model S and Model X on same assembly line, left-hand drive and right-hand drive units all mixed together, (as previously stated: it was like a mini-UN). End of tour had same two Roadsters and three Model S, and a bit of history about each.
2017 Factory Tour. The BEST. Very small group, only five tour participants. So with the tour Guide, it was six total. He drove us to more remote parts of the factory because the vehicle was a single four-wheeled cart, and it could reverse and turn around, not the extended tram (as on previous tours) with multiple carts attached. I had previously met one of the other tour participants (from Austin, TX), and met his wife. Saw beginnings of Model 3 Assembly Line. No sign of the Roadsters and the Model Ss at the end of the tour. We were wowed by TWO Model 3s in the parking lot (employee's cars).
In my Opinion, Smaller tour group is best due to direct interaction with the Tour Guide and seeing several things up close that a tram would not be able to get near.
Worth IT.
Plan ahead, make it happen for YOU!!!