I've got all my 3x great grandparents. I'm missing 16 (out of 64) 4x great grandparents (and actually 3 of those I have names for but haven't created profiles yet due to lack of dates, etc.).
Going that far back, my paternal (French Canadian) side is pretty much filled in. I've got some gaps on my maternal grandfather's side (English) because that brings me back to around 1830, where the records in England get a whole lot harder to search from the comfort of my computer chair. The gaps on my grandma's side (Canadian, a mix of Scottish, English, Swedish, German, and possibly Irish) are straight up brick walls. Which reminds me, I should work on those!