Recommendations for home base and specific day hikes Catalonian Pyrenees

I am hoping for some guidance on this part of a 22-day trip to Spain we will be taking in September 2024. The bulk of this trip will be split betwen two home bases, first in the Costa Brava (Begur) and second in Barcelona (Eixample). We have 4 nights between those two locations and would like to spend those nights in a single location as a home base to explore the Catalonian portion of the Spanish Pyrenees. Although I have found some general information about this region and activities in the region both in this forum, in other online resources, and in guidebooks, I am having diffiulty with the specifics of where to base ourselves and specific hikes. I would love to receive recommendations from others who have experience traveling in this region, particularly from those of you who have done day hikes there. About us: We are a relatively fit 60-year-old couple. We run/bike/hike regularly. This is by way of saying that we can probably handle pretty rigorous hiking, but would like to avoid anything too techical or that would involve actual climbing. We will be in a rental car, so can drive from place to place. We are looking for gorgeous mountain hikes of approximately 5-6 hours in duration (so probably not more than 10-12 miles or 15-20 km). The areas we have looked at for hiking include: Aigüestortes i Estany de Sant Maurici, La Garrotxa Volcanic Area Nature Reserve, Val d'Aran, and Vall de Boi. I would appreciate any recommendations for a homebase situated ideally to explore these sites as well as recommendations for specific lodging and specific hikes. I would also appreciate learning if you have had a negative experience with any of the above (so we can try to avoid duplicating it!). Finally, please don't feel like you are providing too much information -- this part of the trip has been surprisingly difficult to plan. Thank you so much.