Hi prosser,
I'm going to mention rod length again so bear with me please. When thinking about starting out with longer rods especially 2 handed casting rods or switch which are capable of 2 hand Spey casts for me there are 2 reasons maybe 3 to go this route. One would be that you find limited space in some places for a long back cast needed with traditional over head / single hand casting. The Spey style casts eliminate the need for the wide open spaces behind the angler. Second would be that you may be experiencing difficulty in reaching the distances sometimes needed when salmon fishing larger rivers. A Spey rod once you become proficient at casting will make fishing at 70 - 90 feet much easier than most are capable of with single hand casting. The third point would refer to the second, when you find yourself wanting to cast to a greater distance there will be much less shoulder strain experienced because you will not be double hauling 60 to 70 feet of line while getting ready to shoot another 20 into a cast. That process alone can wear a fellow out in a day not to mention ten days.
In view of all that I just said I would be trying to sway you into considering a starting length of 13 feet which would be considered a Spey length and not a switch rod. You can still fish some fairly narrow stream channels with a 13 foot rod and when you are standing on a river or stream with a width of over 150 feet you may be happier with the additional rod and casting reach. I learned with a 13 foot 8 weight without instruction and using a 55' Mid Spey type line. It took focus and a couple years of fishing to sort out all the bugs in my casting but I am very happy that I took the long rod - long line approach. Now I use 14 and 15 foot rods more & more and find them even easier to fish with than my 13's.
This is not to say that there is no place for an 11' 6" rod, I use them for trout fishing on smaller streams and sometimes on larger waters. When you take the 11'6" to the bigger rivers you are limited in your casting range unless you put a lot of extra effort into the casting. If you are looking to be able to fish medium to wide rivers & streams with the minimum of effort the longer rods are going to be the ticket. When you have spent a lifetime casting with 8 - 9 foot fly rods a 13' rod is quite intimidating the first time you rig it up. I know because there was a first time for me. However, if you are a good roll caster you are probably already using Spey casts and just never realized it. The transition to using the long rods is easier if you keep in mind that you are essentially roll casting except that now you have a rod that was made for it.
I am biased because of my own experiences but I do know this; if you learn to cast and fish with long rods and long belly or mid belly lines you will be able to cast any rod or line. I am told that it is not as easy for those who learn with shorter rods and the ultra short shooting head lines. If you are fishing floating lines and un-weighted flies you will love a 13 foot rod. If cost becomes an issue my advice would be to hold back until you can afford a decent 13 foot rod in the 7/8 weight class rather than jump on a switch. If you are anything like the rest of us you'll end up owning half a dozen rods in as many years.
If nothing else I have provided something for you to read

and maybe consider,
Ard