Options for Curved Pergola Rafters

I'm planning approximately a 40' x 16' pergola build from PT lumber for my home. My rafters would be 2" x 6" x 16'. I've considered using a curved design for the rafters (such as the example photo below). In researching what it would take to bend wood it seems steaming or using laminate are the options. I don't have a setup for steaming wood of that length and building the laminate dimensions seems to be an extraneous effort for my pergola size. Not to mention I'm unsure how the laminate and adhesives would hold up to the weather. I've read where some lumber yards may produce curved wood, but perhaps it is only certain wood species? I planned to stain the wood anyway so if I mix wood species (ie: cedar and PT) in my build would it be noticeable? I can certainly call the lumber yards in my area to see what options are available for curved lumber, but I'm kind of at a lost on how else to achieve my design. Any advice is appreciated. Thanks. Curved Rafters http://www.westernredcedarpergolas.com/images/682_ArchedPergola.JPG