Buc-ee's fan here too. I've been on many occasions where there is a line for the ladies room, but with so many facilities available the line pretty much moves constantly.
My favorite thing about it is the amount of variety, which serves my family well. I adore the fudge, my kid leans towards the dippin dots or the icees, my husband usually goes for something healthy like a veggie cup. But we also eat meals there - bbq, grilled cheese, hot dogs, etc. And the cinnamon roasted pecans are like crack! I've never found the gas to be exorbitant but I'm also not fretting over a few pennies difference.