I thought Mac\Charlie's arc was pretty fun. Charlie's exasperation with Mac ignoring his Uncle's affection was exactly the kind of comedy I love about IASIP. And their mother's odd couple thing is always funny to me. The sisters came out of nowhere and added nothing though. That was just weird to me.
I admit I just didn't get the message very clearly with Frank, Dennis and Dee's thing. I feel like I'm missing some social commentary but I wasn't sure where they were going with the 'dogs last day' thing. Maybe some kind of general comment on US sentiment towards firearms but maybe I need to rewatch to get it. I will say Frank and his gun antics always make me laugh so I did enjoy it, just not sure I got it.