I didn't really love "Skeleton" at first...until they opened the set with it the other day and now I'm in love with it.
This album is fantastic. Pretty much agree wholeheartedly with everything you said. I can think of no other band that I've heard that can think of such wittily odd lyrics yet make them work so well and be so memorable.
And yeah, "Twin Sized Mattress" is hands down their masterpiece.