BruceC,
Like you, wife and I will be walking out of Cadiz on our VdlP push on 8 Apr 23. As you note...agree likely wise (and confirmed by others comments here) to book accommodation during Easter week. So far I've found digs (in all but two locations) on the Via Augusta quite easily (and in Seville for a few days). That said, we're facing a first day that is a little longer than I would like (Cadiz to El Puerto de Santa Maria)...just so that we can reach Jerez de la Frontera at a reasonable time on Easter Sunday. Seems there is a fair bit to do/see/taste in Jerez, so also planning a rest night there as well (but have no idea of what might be open Easter Sunday/Monday).
Overall, I'm sort of hoping that by the time we leave Seville (18 Apr) we will avoid the initial post-Easter wave. Yet, I'm reminded of the saying about the 'best made plans'
Buen Camino!