Sure, visiting Kandy, Dambulla, and Sigiriya in Sri Lanka makes for a fantastic journey filled with culture, history, and natural beauty. Here are some tips:

Best Time to Visit:
The best time to visit these parts of Sri Lanka is during the dryer months - January to April for the western and southeastern parts of the country.

Route and Accessibility:
For tourists from the capital city Colombo, Kandy is about three to four hours by car or train. Dambulla is another two and a half hour drive away from Kandy. Sigiriya is a quick 30-minute drive from Dambulla.

Altitude and Acclimatization:
The altitude is not likely to be an issue in these locations compared to mountainous regions. However, stay hydrated, especially while climbing Sigiriya Rock Fortress.

Accommodation and Booking:
Accommodation ranges from luxurious resorts to budget guest houses in all these locations. It is highly recommended to make your bookings in advance.

Clothing and Essentials:
Pack breathable clothing as temperatures can rise, especially in Dambulla and Sigiriya. A hat and sunscreen are essential as well. If you're visiting the Temple of the Sacred Tooth in Kandy, wear modest clothing covering your shoulders and knees.

Health and Safety:
Avoid drinking tap water, stick to bottled water. Make sure to have insect repellent handy. Be cautious while climbing Sigiriya and follow safety instructions.

Local Etiquette and Respect:
Show respect to the local culture and customs. It's considered impolite to turn your back towards Buddha statues while taking photographs. Also, remove your shoes and hat before entering a Buddhist temple.