HI,
Those fine lettuces in the Costco tub I find difficult to clean especially as they tend to stick together. So I have decided to accept the marketing claim, at least it was there early on, of triple washed and simply throw them into the bowl.
When I buy leaf lettuce and Romaine lettuce, I wash them, spin out the water, lay them out in a single layer on a kitchen towel and roll them up using light rubber bands to keep it together. I have clean chilled salad when needed.
At Costco, I also buy those huge bags of spinach. Simply due to their volume, I try to use them fast.