Absolutely, it's a pleasure to assist with your upcoming trip to Hangzhou, Suzhou, and Tongli.

Best Time to Visit:
The best time to visit these places is between late March to May during the spring season and between September to November during the autumn season. These periods offer pleasant weather and beautiful sceneries.

Route and Accessibility:
Hangzhou, Suzhou, and Tongli are well-connected by high-speed trains from major cities in China like Shanghai, Beijing, and Guangzhou. Buses and taxis are plentiful for local travel. Also not to miss is the beautiful boat rides in Tongli water town.

Altitude and Acclimatization:
These cities are at sea level and don't require any special acclimatization.

Accommodation and Booking:
All three cities have a plethora of hotels ranging from budget to luxury. It's recommended to book your hotels in advance, especially during the peak tourist seasons.

Clothing and Essentials:
Pack clothes as per the weather. In general, a good pair of walking shoes, a light rain jacket, sunglasses, sunscreen, and a reusable water bottle would be beneficial.

Health and Safety:
Standard health precautions are needed. Drink bottled water only. Western-style healthcare facilities are available in all these cities, but having travel insurance is advised.

Local Etiquette and Respect:
Chinese people appreciate it if you follow their customs and traditions. A polite bow, minimal physical contact, and modest clothing, especially in religious places, are advisable. Do remember to ask for permission before taking photographs of locals.