If you want to copy the whole database, backup and restore is much cleaner. I'd only recommend snapshot replication if there are only certain tables that you want to copy across to DR. As for your staging database, it sounds as if it's getting updated several times a day, so you'll probably want to look at log shipping or mirroring - or transactional replication if you don't want to copy everything. Given that staging databases are often, by their very nature, entirely transient, it may be sufficient just to keep an empty copy of it on your DR server.

John