I have kind of a digi pet-peeve about double-page spreads, though...I hate it when the beautiful edge treatments of my background paper form an awkward stripe down the center of my page! I want the final effect to be that I added that treatment around my completed layout, not that I used two sheets of paper that already had it done. Know what I mean?
So, here's my technique to create a seamless background for your two-page digi layouts... I'm using PSE7 for this tutorial, but the basic steps will be the same in any program that uses layers.
Step 1: Place your background paper and slide it all the way to one side of your canvas. Duplicate the layer, and slide it to the other side. See how the blue line formed where the sprayed edge treatment meets in the middle? I don't like that...
Step 2: Duplicate the paper one more time, and place it in the middle of the canvas. Now move this layer below the first two so you see the center line again. It'll look like this:
Step 3: Select your eraser tool. Pick out a nice big brush. I've used a 200 pixel soft round brush because I like the way it blends and doesn't leave behind hard lines.
Step 4: Select one of your top layers and simply erase the center line. Your very bottom layer will show through, filling the void and creating a seamless background. Select your other top layer and repeat. Take special care erasing at the top and bottom so the edge treatment blends nicely with the bottom layer. Now it looks like you intentionally treated the edges of a double-page layout, rather than sliding together two single sheets. I think it's much sleeker.
Step 5: Select all three layers of the background paper and merge them into a single layer. This will make your layer palette less confusing as you build the rest of your layout.
Soccer Star digital scrapbooking layout by Chanell Rigterink Credits Digital Kits: Let's Go Mini by Robyn Meierotto, Kitschy Hearts by Akizo; Frames: Old Vintage Paper Frames II by Maybemej; Sketch: 297 by Scrapbook Challenges; Fonts: Carbon Type, I Love Derwin
EPIC digital scrapbooking layout by Chanell Rigterink Credits Blue and Orange Papers, Mask: Crazy Kit by SAS Designs; Grid Paper: Sea Wonders Kit by Isabel Mendez; Brush: Arrows by Lucaliverti; Brush: Dynamic Stitching Brushes by Amanda Sok; Sketch: Katherine Hanson; Font: Joyful Juliana
And a couple more examples from my archives...see how the edge treatment goes around the whole layout and not down the center?
Evan Rocks digital scrapbooking layout by Chanell Rigterink Credits Digital Kit: Birthday Boy by Faith True; Sketch: 281 by Scrapbook Challenges; Font: Baby Boston