ACCENT WOOD
For your accent woods consider Bamboo ply in the same color family as your wood floors. The perk of bamboo play is the beautiful inlay patterns that occur naturally at the cut edges of the wood.
PAINTED WOODS
For painted wood elements how smooth you would like the finish to be in the end is the consideration at hand. If you want a very smooth paint finish low voc and formaldehyde MDF is an option. If you want have a subtle wood grain under a color plywood is an option with either a white stain or a glaze that would make the graining pop back out after painting.