Breed Ideas? Biased people WELCOME!

I am trying to decide on a breed and/or mix breed (would look for these mixes if I adopt from shelter or petfinder). I have the chance to get an Aussie, but I want to make sure all of my options are explored before I make this big decision. (I didn't struggle this much over my apartment or car choice, BTW.)

Here are the things I'd like to have:

*Smart, pretty easily trained
*Basic tricks
*Maybe play ball/frisbee
*Attractive (aren't they all?)
*Good with older kids (mine is 7, visited occasionally by a 3 year old)
*Needs moderate exercise
*Eventually would like to get my daughter into 4-H with the dog
*Barking would be a problem as we can hear our neighbors all the time! (I can't wait to move to a house!!!)
*Small to small-medium dog (Avoiding toys or gargantuan dogs. LOL)


My facts:

*I live in an apt, second floor. Large floor space to play, and large yard/field in back right out our door.
*Off in the summers, work during school year 7 hours a day. Would be crated.
*I have a 7 year old daughter that NEEDS a companion and is very responsible and dog savvy.
*We walk about a mile or more each day and go to the park a couple times a week and walk even more.
*We have time to devote to play and training every day.