The bird's nest and water cube are easy to go. You can visit it on your own. The guide would also not explain to much to you.

I feel regret to say sorry to you. It is quite complicated to visit Bird's Nest and Water Cube. Firstly, cars are not allowed to park outside the sites, it is quite a distance to the gate of the site. Thus, it should be tired for you to reach there on foot. Secondly, the ticket office of Water Cube is far away from the site. It takes at least half an hour to buy the tickets. Besides, visitors are only allowed to have the sightseeing according to the time shown on the tickets, which is quite inconvenient. Why not visit on your own?