Absolutely! In fact, getting to know Oviedo, Gijón, and Santander is a fascinating journey. Here's some handy guidance to make your travels smoother:

Best Time to Visit:
The best time to visit these cities in Spain is from late June to early September when the weather is warm. Also, consider visiting during April-May or September-October for relatively fewer crowds.

Route and Accessibility:
These cities are well connected by trains and buses. Oviedo is approximately 30 minutes away from Gijón by Train. From Gijón to Santander is about 2-3 hours by train depending on the service.

Altitude and Acclimatization:
These cities are all at sea level so there should be no acclimatization issues related to altitude.

Accommodation and Booking:
Booking in advance is advised as these cities are popular during summer season. Accommodation options range from guest houses, bed & breakfasts, to luxury hotels, depending on your preferences and budget.

Clothing and Essentials:
Pack clothing suitable for warm weather, but include some layers for occasional cooler evenings. Don't forget your swimsuit if you plan to hit the beach in Gijón. Comfortable walking shoes are a must as these cities are best explored on foot.

Health and Safety:
Ensure to stay hydrated and protect yourself from sun with sunblock. All cities are generally safe but usual precautions should be taken with personal belongings.

Local Etiquette and Respect:
Spanish people value politeness. When entering shops, greet the shopkeeper. It is also appreciated to try to speak a bit of Spanish, even 'hola' or 'gracias'. Be respectful of siesta time (usually 2-5pm) when many shops close.