I'd like to start designing invitations and need to know what the best Adobe program would be for this. I will need the ability to add graphics and text to the photos. The files will be sent to my customers in PDF version and they will be able to print as either a 4x6 or 5x7 photo.
Any info appreciated.
I'm surprised nobody has weighed in on this one.
In my opinion the answer is the best application is the one that will do what you want and that you are comfortable using. Photoshop, Illustrator and InDesign are all capable of doing what you describe, I think. Photoshop limits you to a single card per file, while Illy and ID would allow multiple pages, and different sizes, in one file.
My personal bias is towards InDesign, but there are pleny of Illustrator power users who would disagree.