We have already shown you how to add your own backgrounds to save yourself some time using your favourite background again and again and also how to use the opacity option to change the look and feel of a page.
Another thing you can do is using things like maps as background. Think of city maps when you visited a new place and walked around exploring with that map. Or maybe you have done a race where they gave you a map or you have drawn your own itinerary on a country map connecting all the cities and places you visited when you were there on holiday. A drawing like that would be great to use as a background for your holiday photobook.
Imagine you did your trip-of-a-life-time with a campervan through Australia and you travelled some sections with the train for a different experience. You could add something like this as a background to all your pictures as a reference to the big trip. And don’t forget to add it as an image somwhere prominent too (for example at the start of your photobook where you describe the route briefly).