Well, for an HO scale layout, I'm partial to Roco's Rocoline track. It's code 83, comes with detachable rubber roadbed (which looks awesome and is quiet as anything! ^_^ ), and is available in a wide variety of pieces! (Rocoline is available in anything from squeaky yard only curves to wide 35" inch-radius ones and even some nice, wide 70" inch radius track!) Rocoline switches are some of the smoothest ones I've ever seen, and all trackage measures out "neatly" so that one way or another, all tracks fit together nicely.
I wish not to sound like a zealot, but Rocoline track is probably some of the best ballasted track out there for the simple reasons that it's available in more varieties than Kato Unitrack or Atlas Snap Track, and it's much better quality than Bachmann's EZ Trak. Try it! ^_^
By the way, the two best places to find Rocoline track are
www.reynaulds.com and
www.tee-usa.com. Both are European import shops and they carry the stuff at decent prices.
Oh yes, and I assume that since you run Amtrak equipment, Viewliner, you'll want nice wide radius curves. Twenty four pieces of R9 and R10 track gives you 32.5" and 35"-radius loops, fine for running Amtrak coaches. I use 10 degree switches on my layout and they're great for a smooth, relatively high-speed crossover or exit into my yard area. (Use 2 R20 pieces to make track parallel to a 10 degree turnout.)
One word of warning, though: The Rocoline switches are "DCC friendly," and I dare not try to power route them for fear of ruining them. If you still use old-fashioned DC control, find a way to stop power from going to each side of a switch, or upgrade to DCC. Otherwise, you will have an awkward time trying to control two trains at once if you do that.
Anyway, best of luck with your new layout construction! ^_^
(*subliminal message*Use Rocoline track!*subliminal message*) ^_~