Warm Wishes or BQ pattern showcase a large piece of fabric.

I think it's a good idea to use one for the top and the other for the backing.

I think I just saw this here the other day. Just another idea, but I really like the ones already suggested.
http://www.maryquilts.com/twisted-happy-block-quilt/

Could you take each of the snowboarders and add a couple thin borders around each to make them bigger main blocks? Add in coordinating fabrics as fillers, add borders. Use car fabrics to make a creative back. Just ideas..........

Look at patterns using charm packs. They have so many that highlight a 4" center square. This would be perfect for your snowboarder print. Think about patterns such as churn dash - large center piece with either HST or flying geese around it. You could alternate these blocks with the same block featuring the cars print (or using the cars as a backing would also be a good choice).

Why not an Attic Window for one of the prints and then use the other as a backing? Or could use both (alternating) in the Windows, maybe?