I used to have an a6 wagon, we had a box for a while, recently got rid of it and sometimes use the built in bag or keep it flat. I just got an a4 wagon last spring, and I am trying to figure out what to do. I don't really want to do a box again because I don't like the look as much, and they add a ton of drag. I also need to get a new bike rack, so I will have to consider that. It might be easiest to just get the clamp style ones and then wipe off your skis every time. I also want to find ones that are low profile incase I get lazy and leaver them on, and I just don't want them sticking out super far. Last thing to remember is that a box will usually cover your sunroof, if that matters to you.