I like to stick with white backgrounds for my travel photobooks, though these templates do feature a painted background layer which I changed to a soft fairly neutral colour into which I then blended the photos (clipped to the messy masks) using various blend modes:
Just clip and merge your photo and the clipping mask then play around with all the different blend modes - color burn, hard light, overlay etc etc - to see which one you like the best.
(And you can always "layer them up". If you like the effect of one blend mode but it's a bit too "extreme" then just duplicate the layer and put the top layer on "normal" or another blend mode and reduce its opacity until it looks perfect.)
You can even use a photo as the background, as I did here:
But the possibilities are endless ... you can use the blended style spots for patterned paper instead, as Christa did here:
EHStudios even used one of the photo mats for fun patterned paper and went for a gorgeous bold background in her second page:
And look at this gorgeous page with lots of goodies added by Anne :-)
And even more goodies and a one photo layout from layering guru Iowan!