Mark, I switched because I needed an automatic. The Golf and Jetta were close to last on my list for small cars with good automatic transmissions but after reading a little bit about their reliability (Siraqua helped on this) and driving a TDI w/ Auto (5 speed too!), I was convinced. Heads above a Mazda6 I4 w/ Auto, and similar to an Accord 4-cyl w/Auto, which is great.
There's no difference inside a Jetta vs. a Golf, except maybe an inch for rear passengers headroom. I'm gaining a lot of trunk space though! You can fit a lot more luggage in the Jetta than the Golf... but you can't put in big boxes, or small freezers, in the Jetta... it's a tradeoff I didn't mind since we'll probably end up buying a small SUV in 3-4 years, something like a CR-V.
And siraqua, the Jetta is great! None of the "tocking" noises coming from the ceiling I had in the Golf, no creakings around the radio dash either. One of the rear tweaters really doesn't like AM talk radio though, not sure how to describe it, it emits a kind of vibration, but I'll have that fixed on my next oil change.
The only other thing is the driver seat's leather side bolster that rubs against the side of the center armrest which is plastic. I'll wait a bit and see if it does the same thing when the leather isn't cold... if it does, I'll put something in between the side bolster and center armrest to prevent the friction.
Other than that, #1! Oh and it looks INCREDIBLE!
Still waiting on some nice weather to go wash my car and post pics of it...