I like It's Always Sunny for all those elements. It's a quick show to watch, keeps me entertained, and they always get into some crazy hi-jinx. I'd say it's true that there isn't really much growth per individual episodes, but there are little things that will get referenced here and there throughout a season that do help flush out the characters.
To me it's a cross between Arrested Development and The Sarah Silverman Show. It's got really good writing like AD, but more fart/poop jokes like TSS.
Off the top of my head some of it's highlights are:
