Russian Imperial Stout!!!!...
Not an option??
Ok, then Scotch fer sure with the T 52. If you have a nice sipping rum, that would be my suggestion for the Dirty Rat though.....some nice sweetness to off set the spice of the DR. A good rum goes amazingly well IMO with a Dirty Rat (and the T 52 as well for that matter).
And to your other question, speyside would be the Scotch of choice (for me at least) for the very reason of adding that hint of sweetness. They're typically sweeter Scotches than the Islays (which are more peat/smokey characteristics). I'm not talking "sugary" sweet, but more vanilla, nutty, caramel notes etc. (i.e. a nice Macallan 12 year etc.).