I plan to do California Capitol Corridor which uses the old SP main line from San Jose up to Roseville yard (yea I know it goes a bit further, but I always stop at Sacramento). I will also include Niles Canyon all the way up to Pleasanton. The route will be based largely on what the line looks like today, with a few of the industries from the 80's put back in just to add the ability to roll the clock back and run a bunch of bloody noses around

The whole route has personal significance to me as I grew up in the Newark/Niles area and watched SP (and UP) roll by and take the CC up to Sacramento a number of times to visit the railroad museum. I was able to spend time at both Niles Tower and East Oakland Tower before they were closed down, and met a lot of great people. Today both my sons love the drive to the canyon to see and occasionally ride on the trains of the Niles Canyon Railroad, and during Christmas we use up what is left on my ACE ticket to ride down to San Jose for Christmas in the park.
So far I figure I have 48+ miles of mainline laid out with a few bits I need to rip and replace, and I have two yards done (Santa Clara and Newark), with two more in progress (Fruitvale and the Oakland Intermodal Yard)... gonna take a year I figure, maybe more.
http://2.bp.blogspot.com/-4oXMp9mB6vM/Talk0lBC9HI/AAAAAAAAASY/qGxPrKf9OEk/s1600/San+Jose+Diridon+Station+%25282011-04-16%2529.jpg
http://1.bp.blogspot.com/-8suy5eqtBek/Talk3I8UnoI/AAAAAAAAASc/rcIrpbeIKlY/s1600/Santa+Clara+Station+%25282011-04-16%2529.jpg
http://4.bp.blogspot.com/-jD5m1FVSKOA/Talk4zfc_0I/AAAAAAAAASg/pa95NF5_da4/s1600/Newark+Juction+%25282011-04-16%2529.jpg
http://2.bp.blogspot.com/-miC_rDfO-QE/Talk6lUYJUI/AAAAAAAAASk/gwc-RoKNopQ/s1600/Niles+Junction+%25282011-04-16%2529.jpg
http://1.bp.blogspot.com/-ABGPJPY7Azo/TalX7xCx1vI/AAAAAAAAASM/mC-bAAT4vd0/s1600/Oakland+Intermodal+Terminal+%25282001-04-15%2529.jpg