Lisbon, Cadiz, Malaga, Ibiza and Barcelona are all cities you can do on your own. Wonderful places to explore. No need to book any excursions. Cadiz and Malaga have amazing food markets to visit and eat.
DO NOT waste your time going to Gibraltar. It's a cluster with having your passport stamped. The day is better spent in Cadiz.
Seville and Granada are more suited for land trips given the hours spent driving back and forth.