As you go upstream away from the falls themselves in a very short distance you can turn off for Dufferin Islands; do it. It is a lovely small park formed in what is essentially a sort of bay of the Niagara River. But in contrast to roaring cataract itself and the rushing water in the main stream of the river this is a tranquil setting of small island, streams, paths and bridges. Even in high summer you will have no problem parking (for free) and no jostling crowds. It is a pleasant, peaceful place to walk around with enough variety to be interesting but small enough not to be tiring.