Dyes to bind to double stranded DNA?
Most of the dyes used for visualization bind with a much higher affinity to dsDNA. This would be SybrGreen, EtBr (although this will bind RNA as well).
There is a pretty comprehensive website from Life Technologies about Nucleic acid stains that is worth a look.

There is as well a publication on this topic: "DNA Staining for Fluorescence and Laser Confocal Microscopy"