Ask an Engineer. Oh wait, I am one.
You have some good suggestions here. Bargello is great, some intricate log cabins work well because the blocks can be used in so many many ways. The Illusions book is pretty good too. Tumbling blocks.. nice but it will get boring after awhile. Remember males like dark rich saturated colors, fall and winter themed.
Engineers like complex patterns with simple solutions. The best engineers love elegant solutions that require a minimum of work. It's how we think.
tim in san jose