Went to a meeting at City Hall about some potential arena/intermodal designs. Here's the latest plan for the arena/intermodal area:
Sorry for the low-res cellphone pic, there will probably be a better looking copy online in a day or two.
In this version the arena is back over on the west side of the lot, with the transit uses on the right, and an open plaza in the middle where transit passengers can move back and forth and arena patrons can enter and exit where the blue arrows are--allowing them to walk into Old Sacramento or to the transit center with equal ease. The red spots are retail pads for joint development--shops or restaurants for use by arena or transit patrons. The depot becomes the main entrance from downtown to the whole complex, once you leave the depot the trains are straight ahead and the Shops provide a backdrop. Due to its location on the west the arena itself provides shade in the afternoons to people walking to and from the tracks. The tracks and the Shops are accessed by the tunnels currently under construction, although additional paths over the tracks wouldn't be ruled out, and the idea of cantilevering the arena over the tracks to the north could be extended even farther here.
There is no access for cars other than drop-off points in front of the depot and on the eastern side--except for trucks/buses servicing the arena, accessed by a service road indicated by the dotted black line.
I still have my concerns about the financing plan (and so do the Maloofs, apparently) but from an urban design standpoint, if you're going to jam an arena and an intermodal depot on this small lot, this looks like a good way to do it.