My solution to siphoning the sand is this, I have black sand in my tank and what I do is use a 1" hose and just hover over the sand to pick up debris. The 1" hose uses alot of vaccuum so it works well. I would go with black and brown gravel by the way. That looks good.
I definately think this is based on personal opinion. I'm not a big fan of white sand, but have had both tan and black in my tanks. I prefer the black.
don't use sand. if your fish dont need it or if they are farm raised, **** sand. dont use anything. using substrate slightly raises the difficulty of any and every aquarium. bare to plants. otherwise dont use anything b/c it is ridiculous. substrate is stupid.