I will be travelling to Zurich next August 2011 and plan to have a Full Swiss Rail Pass for unlimited travel throughout Switzerland. We want to take a side trip to Lake Como for a couple of nights. I know that our rail pass would get us to Chiasso for no charge with the pass (at least I think it will, maybe someone can explain the red dashed lines on the swiss rail pass map. Red dotted means supplement, but I think that red dashed means a tunnel ???)
Anyway, the trip to Como by train looks like an additional four minutes, but if I try to price tickets from zurich to como, I can not seem to find a price that accounts for our rail pass.

Do you just by the ticket in Chiasso? Does anyone have experience with this?

Yes, the dashed lines mean there is a tunnel there. that is a pretty route despite the tunnel(s). There are several very short ones not shown on the map.

Your pass will take you to Chiasso; you could buy a ticket for the short distance extra to Como SG before you board. I believe seat reservations are required on that train, so you would need to visit the ticket window to purchase those. You could do this several days in advance of travel if you like.

Trenitalia is quirky. Enter a date within the next day or two for the trains from Chiasso to Como show. These are mostly R trains and very cheap (no reserved seats). Cost is only 1.05€.
http://www.trenitalia.com/cms/v/inde...0080a3e90aRCRD

From Zurich to Chiasso, I would assume you would have to select that on SBB.ch. Watch for specials though as sometimes they have this route for 30chf from Zurich to Milan with advance purchase (other pass specials also). If you run across a Zurich/Milan special, it might be cheaper than booking just to Chiasso. You can hop off the Zurich/Milan train in Como (stops at S. Giovanni).

On the SBB website, you can specify that you have a Swiss pass at one stage in the booking process by choosing "discount Switzerland" (or "Ermässigung Schweiz" in German).
It will be easiest to buy a ticket at the ticket office in Zürich, and show your pass to get the appropriate reduction.
In either case, you will only need to pay a tiny fare to cover the journey from the border to Como.

It will be easiest to buy a ticket at the ticket office in Zürich, and show your pass to get the appropriate reduction.>

Geoff is saying you get discounts on Italian trains by having a Swiss Pass? Sounds great - Swiss Passes are already great deals! Or maybe I misunderstand, as usual, what Geoff means by 'get the appropriate discount?' As he is always right I guess I can just take it as gospel?