Inside the Cockrell Butterfly Center you will find both steamy, and cool relaxing environments. There is plenty of wonder, including plants, flowers, iguanas, and of course butterflies. There is also a large waterfall which provides a nice background audio track as you enjoy the different levels of the exhibit.
In Hermann Park, there is a small Japanese Garden that you can visit. It is a nice spot and home to several special plants, gold fish, and turtles. I was thinking that it would be great to visit in the springtime when everything is in full bloom.
The Sam Houston Monument in Hermann Park is a pretty impressive sight. The area includes a reflecting pool, the bronze sculpture, and several gardens which may or may not include passing butterflies. When the sun is shining, it makes for a great photography spot.