Hi Tamara,
I like the way you have rotated the house on the block to give better access to the front entry. You now have plenty of room in front of the Alfresco and around the pool area for some inspirational landscaping and entertaining area which should look spectacular.
With regard to your colours for the vanities you can certainly get both Black and Charcoal in Flint finish (semi matt with slight texture) we use the black frequently at work for desks and counters.
This a link to Laminex colours for reference:
http://www.allgoodfurniture.com.au/docs ... ersion.pdf
Hope this helps