Bright geometrics enhance the cloth's appearance.
Tropical foliage is contrasted against tribal geometrics.
I do remember some theories concerning relativity suggesting some sort of motion in space might allow time travel if space-time geometrics are possible.
More visually interesting than solids, geometrics can work well with a tailored room style or can create a backdrop for a more eclectic look.
West Elm offers a high quality selection of classic styles, geometrics and hippy chic, appropriate for older teens.
For a true cottage look, try the Caroline bedding ensemble which has a seamless grouping of plaid, mini floral, pinstripes, and geometrics.