The last two times I was on Iberia in coach, I had assigned exit row seats verified the day before and then when I went to get my boarding pass, I didn't and of course, they are taken so I ended up way back in coach.

FYI - boarding Iberia flights is chaotic to me but they do call for OW elites to board before the rest of coach and they don't seem to care about the carry-on sizes either (I have had problems in BA with this).

I have transited several times recently through Madrid and found it easy and great lounges.