My group does a lot of PAD work. I prefer CTA abdomen with run-off. Just the other night we had to repeat a CTA abdomen with run-off because the ED ordered a lower extremity angio, and there was partially visualized clot extending from the abdominal aorta into the common iliac, so a repeat was done to fully visualize the extent of the clot. We would also want to know about AAA if a patient had common iliac stenoses and potentially needed kissing stents, and I've also seen a case where the problem was bulky calcification causing narrowing of the abdominal aorta. Including the abdominal aorta doesn't add much scanning time, and excluding it can sometimes miss some critical findings.
Keep in mind that proximal stenoses can result in distal lower extremity symptoms.