Susan and I have chatted about this topic on several occasions recently, with our couples invites going out right around the USPS's May 11th rate hike. You need to be aware of how this will affect your reply cards.
We think the blog from the Martha Stewart team does a great job answering all your questions. Check out their story.
I think that the Forever stamp is the way we will be going over the next couple of months....appropriately named for wedding replies, don't you think? :-)As always happy to share our 3 cents, or in this case .42 or .44.
Love, the Bella Girls