Advise how to travel from Guangzhou Airport to Zhejiang mainland/Hangzhou or from Shanghai Airport to Hangzhou airport

From Guangzhou to Hangzhou, it is around 1,300km between, so u are highly advised to fly there and it will take no more than two hours.

There are two airports in Shanghai. Which one are you referring to? If it is PVG, you can take a direct bus to Hangzhou ad then take a taxi to Hangzhou Airport. If it is Hongqiao Airport, you can walk to Honqgiao Railway Station to catch a high-speed train to Hangzhou. Then you can transfer to airport shuttle bus to the airport directly.