I would vote for lenthwise. I'm *guessing* that your going to have multiple repeats of the fabric on at least two sides, and if so I don't think matching the sides to each other is necessary at all. Do you plan on mitering the corners to match top to side? If so, you'll need a bit of planning for that (and I don't envy that task!). A way to get around matching the top/side seams though is to use corner blocks. Is there a block in the quilt you can repeat?