I use mine all the time and can't imagine having a bike without it. I recently took a trip with my kids and divided up the stuff. One carried the beach towels; one carried our change of clothes; and I carried bike supplies; first aide kit; money; ID; lunch and sunscreen.

When bike commuting to work I carry a change of clothes and towel for the work shower.

When I bike to the beach I carry a bathing suit; towel; sunscreen; food items; money and ID; and running shorts for when I go into stores to cover my snug bike shorts; Oh also a vented cap to cover my messy head when I take my helmet off.

I was using a flexible cooler bag with bungee cords but then recently purchased a nice trunk bag which fits better and doesn't need bungee cords. I do however tend to over stuff it and so I do use one bungee cord because the velcro straps aren't an exact fit and aren't long enough. I should try it on another rack and see if it fits better - then swap racks I think.