The places visited will have an official tourism agency with recommendations for licensed tour guides.

My view is that if you do those 3 cities you will not have much time for side trips. Maybe reconsider. The area around Barcelona is wonderful and can easily fill weeks. Same for Portugal. The more cities/sites you want to visit the less you will see.

Lots of wonderful hotels to be had with charm and character - e.g check https://paradores.es/en for Spain and https://www.pousadas.pt/en for Portugal. You can combine better value options with high end to keep to $500/night easily. there are also outstanding B&Bs that can be considered true luxury.