Stouts -- no particular favorite. I have Guinness more than anything, but at places with craft stouts, I'm always willing to try another. Some of the craft ones I've had are really stout.
Scotch on rocks -- normally Johnnie Walker Black, but any of the nicer blends or mellower single malts will certainly do. I draw the line at Laphroiag, way too iodine tasting for me.