Ed Kindle has put together a great collection of old Erie postcards on Flickr. A few of them show Waldameer, like the one here.
As you can see, there once were beautiful flowers marking the entrance to Rainbow gardens, hence the name.
By my count, there are eight more Waldameer postcards in his collection. Here are the links to the rest. Put on some Erie-ish tunes, sit back, and enjoy!