Sure, I would be happy to assist. Visiting the cities of Jeddah, Medina, Mecca, and Ta'if is a great way to experience Saudi Arabia's rich cultural heritage.

Best Time to Visit:
The best time to visit these cities is during the cooler months, from November to February, avoiding the intense heat of the summer season.

Route and Accessibility:
Jeddah is accessible through King Abdulaziz International Airport. Mecca and Medina are just a drive away. However, please note that Mecca and parts of Medina are only allowed for Muslims. Ta'if can be reached by road from Mecca.

Altitude and Acclimatization:
The cities lie in the coastal and desert region, hence no particular acclimatization is required. However, remember to stay hydrated as the climate can be quite dry.

Accommodation and Booking:
There are ample accommodations available including luxury hotels, apartments, and budget accommodations. Remember to book in advance especially during the Hajj period which sees a huge influx of visitors.

Clothing and Essentials:
Saudi Arabia is a conservative country, it’s recommended to dress modestly. Women should carry an Abaya(to cover the whole body). Sunscreen, hats, and glasses are recommended to protect yourself from the sun. Always keep in mind to respect the local customs and traditions.

Health and Safety:
Carry basic personal medications. Hospitals and pharmacies are widely available throughout these cities. Be mindful of your belongings in crowded areas.

Local Etiquette and Respect:
Saudi Arabia is an Islamic country with rich traditions and a code of conduct. It’s important to show respect to local customs. During prayer times, shops close for a short period of time. It's best to plan your shopping around these times. Drinking alcohol is strictly prohibited.