IMO, beauty is in the eye of the beholder. I believe that while appearances can sway decisions, it should not be very high up on your checklist.

How much exercise can you provide?
Will you be adopting or buying? If you're buying, stay away from pet stores and BYBs. Try to pick a breed and go to its parent club. For example, if you want a Chihuahua, go to Chihuahua Club of America and click on breeder referrals.
How often can you groom?
Small dogs and young children do not necessarily mix well no matter what the breed. Young children are just inclined to pinch/hit/etc. It's your job to supervise all dog/kid time.
Will you be attending obedience classes?
Have you looked in your local shelter?
Go to Petfinder.org . I guarantee you that you can find a small breed dog *somewhere* in your area.
Active dogs are often active throughout their life. Can you provide all that exercise? I know I couldn't, and that's why I'll stick to my Pekingese and Greyhound. Also, I don't think a Pekingese would work in your situation.
Good Luck and please consider the adoption route. The rewards will be tenfold