The downside to doing a scrappy strip quilt with all 2.5" strips is that you will need to match the joins (also, you can't count on all of the strips actually being 2.5" wide). Luckily someone pointed that out to me before I used my Accuquilt to cut my scrap strips. It's a much easier quilt to make if you have random size strips.
I would do a rail fence.
bkay