Additionally, while in Spain looking for a city that we may want to stay at longer term, say 90 days. We live in Colorado and enjoy the mountains but also enjoy the beach. Could we find a great place close to both?
Yes! Catalonia is one and the Valencia region is another.
Actually Valencia is my new favorite city in Spain, clean, welcoming, safe, and undertouristed. From Valencia you have many options, you can head south to explore La Albufera Wetlands National Park, where Paella originated from. You can also head north and explore the less touristy Costa del Azahar, Peñíscola is certainly worth a look, a Knights Templar crusader castle on a rock that juts out into the sea, surrounded by a whitewashed old town, very Levantine.
Inland from Valencia you find the ancient ruins of Saguntum, which Hannibal invaded to start the the Second Punic War with Rome. You can also head west on the AVE train and explore Cuenca, with its unique medieval town hanging from a cliff. Good hiking nearby in the Serrania de Cuenca National Park (which are mountains), but may need a car.
AND if you do have a car at your disposal, even for a few days, I can strongly recommend a multi day side trip to the nearby Matarraña region. I was just there for 6 days and it was wonderful. Rolling hills, olive groves, medieval villages, and crystal clear wild rivers you can swim in. The best part it is totally undiscovered by foreign tourists!
Here are some of my pictures from our road trip - https://photos.app.goo.gl/sMsd6Wz2fydGKYtr5
PS: also know the 90 day limit for non-EU nationals.