How long to visit Xixi Wetland Park for

I think you'll need to plan a full day at Xixi. Many Chinese people spend 2 days here, but I don't think you need to do that:

• Getting there and back will take 1-1.5 hours in each direction from the city. There are hotels around Xixi area but it's in the middle of nowhere so I don't recommend staying here
• Inside the park, I suggest taking the boat to get around, which will be faster and less strenuous. The park is massive (probably the size of the entire Hangzhou city center area) so walking around will simply take too long. With boat, if you don't get off anywhere the ride will take about half a day. If you want to get off at some scenic spots, it can easily take a whole day