Absolutely, visiting Madrid, Barcelona, and Valencia will introduce you to the vibrant and captivating culture of Spain. Here are a few travel tips for your journey:

Best Time to Visit:
The best time to visit these cities is in the spring (March to June) and fall (September to November) when the weather is pleasant. Summers can be hot.

Route and Accessibility:
Madrid, Barcelona, and Valencia are well-connected by high-speed trains (AVE), making it very convenient to travel between these cities. Local transportation includes buses, metros, and taxis.

Altitude and Acclimatization:
These cities are at a low altitude, so acclimatization isn't typically an issue. However, do remember to stay hydrated, especially during the hotter months.

Accommodation and Booking:
Spain offers a wide range of accommodations. It's best to book in advance, particularly during high season and during local festivals. Consider staying in city centers for easy access to attractions.

Clothing and Essentials:
Pack for the season you are visiting. Summers are hot, requiring light clothing and a hat for sun protection. Spring and fall might require a light jacket. Comfortable walking shoes are a must as these cities are best explored on foot.

Health and Safety:
Spanish cities are generally safe, but watch out for pickpockets in crowded tourist areas. Stay hydrated in the heat, and don't forget to purchase travel insurance.

Local Etiquette and Respect:
Spaniards are known for their friendliness and relaxed lifestyles. Respect their traditions and customs. Spanish people often dine late, and siesta (afternoon rest) is common in certain regions. Dress modestly when visiting religious places and maintain decorum.