That tank cleaned up pretty well. Even comes with Snow White. Perfect!
If you are using an external canister filter for the 55g, you have factor in some under tank space for that which would take away the look from the two tens. I'm assuming that there will be a center brace between the two tens? If so, the canister could go right in the middle. Or you could mount the canister to the side of the stand.
Take a look at your local fish store the next time you are there and measure how high their lowest tank is from the ground. Then imagine you are in your house and think about whether you would enjoy looking at those two tens at that eye level. I would suggest raising it up slightly than having it just 4 or 5 inches directly from the ground. Just remember that you need adequate space between the top of the 10 gallon and the roof of the stand to perform adequate maintenance (e.g., can you get a good siphon going to vacumm out the detrius from the tank bottom to the bucket?).
The 2 x 4's could be painted out and then you could cover them with a nice skeleton shell. Just remember the inside walls.