I am so glad you are researching both breeds to see which is the best fit for your family. Picking between a Maltese and a Yorkie is like choosing white or dark chocolate! A delicious, but difficult decision.
Just a word of advice......
You will find more Yorkie puppies available in your area than Maltese. Due to their popularity, Yorkies are a favorite of backyard breeders (greeders) so they are more easily found. If you get a puppy of either breed from a BYB, you won't get a good representation of a Maltese or Yorkie anyway so your careful research will be wasted. The only way to guarantee you will get a puppy who will grow up to look and act like a Maltese or Yorkie is supposed to is to get one from a reputable breeder.
I suggest you start with breeders recommended by the breed club and go from there. They will be able to direct you to other breeders.
American Maltese Association Breeder Referral Yorkshire Terrier Club of America
This is a wonderful article no matter what breed you choose:
Maltese Show Dog Versus Maltese Pet.....What is the difference?
Here is a great guide to finding a reputable breeder:
Backyard Breeder vs Reputable Breeder