First of all read the article by the venerable Bob Veverka on our Destinations section http://www.flyfishingforum.com/destinations/index.htm
I would think that a stout single hander in a 10/11wt would be handy if you are going to pursue bull dorado or small tuna. Tim Rajeff's Echo series are very impressive as are TFO if you want to keep the investment reasonable.
The switch would help from shore or where big grains and long shots are needed. I have found two-handers from a boat to be great tools provided they are not over 11ft long with the proper handle config. I designed a rod to have the top grip to tip be about the same as the single hander grip to tip but handle twice the grains with less effort. I found it to have distinct advantages in certain situations.
I'd think hard about the reel you bring as well, these fish don't mess around once hooked.