To help break up the monotony of scrapbook pages you may want to use various shapes: circle, oval, triangles, octagon and hexagon.
As you design your pages you will find many opportunities to uses these various shapes to help in bringing focus and continuity.
Both the circle and oval connotes unity and infinity. They enclose with a sense of protection things found with in them. Their curved lines lend a softening to the stogy straightness of squares and rectangels.
Circles have an equidistant plane from a common axix. We think of "O" as a circle.
Ovals are similar to circles except they can have varrying distances of plane from a common axis--an egg shape.
Or from two axis--which makes an elliptical oval. This is the oval most used in scrapbooking because there are more cutters for this type.
Circles and ovals can provide excellent photo mat cutouts. They can serve as areas to do your journaling in.
Cutting or making circles is easy with many tools and machines available:
Ovals are similar to circles except they can have varrying distances of plane from a common axis--an egg shape. 
Or from two axis--which makes an elliptical oval. This is the oval most used in scrapbooking because there are more cutters for this type. 