Males Vs. Females
There is always the big question when buying a puppy.... girl or boy?
The biggest thing to look for is the puppy's personality and your family
lifestyle.  I have had the wonderful experience in having and raising both
and have found that it really depends on your activity, training, and time.
Girls can be just as great as boys, but when left unaltered, they will be the
hierarchy of the household. Girls love attention, but when they've had
enough...they've had ENOUGH.  With all of my years experience with girls
and boys, I have only had to break up fights between females. They are
the ones to establish the pecking orders and maintain them. They will
also "hump" and "mark" just like the boys. There is a reason that the
word "bitch" is also used in a derogatory manner.
Males are the ones that will never grow up. You will find that a male will
always want attention like they are starved of it and will act like a puppy in
many ways until they are grey and blind. Most males will always want to
play and will stand by for any willing hand to pet them, while females still
love attention but will grow regal and dignified with age. It is kinda like the
witty grandpa playing with the grand kids while grandma sits on the
porch swing and watches.
Males can be very defensive of                                                    their "girls"
and of their families. It                                                                   is very
important to teach manners and                                                       obedience
to your dogs. Also, if they are                                                          allowed to
mature with their "manhood" they                                               can also learn
to mark, lift their legs, and wander.                                                    If you are
not planning to breed, it is best to                                                        have your
male puppy (or female)                                                                          neutered or
spayed when they reach 6 months                                                 of age.  Then
you don't ever have to worry about                                                        them
wandering to the neighbors yard or                                                       ever
developing prostate cancers                                                                or tumors.
Females, when allowed to mature unaltered,                                       will have
"heats" which is similar to the human                                               period.
They can have mood swings and can be stand-offish. They will also seem
to pout when they don't get what they want when they want it.  You will
also have to deal with the bloody messes secreted when they are in their
heat cycle. This can be a BIG mess when you are not watching for it!
There can be very little difference between a male and female when they are fixed at a young
age.  I have heard many stories about our puppies that have went to fabulous homes where
they were protective of their families, comforted the kids when they were learning to sleep in
their own beds, and were happy companions in the car.  
It can be very important when you don't know which one to get to see the whole litter.
Although, with the Internet, selection may be a lot harder when people are buying puppies at
an early age. The best time to see a puppy's personality is in between 4-6 weeks of age.
This time is really important as you can see their personalities budding and they are learning
to play. When wanting to know about the specific behaviors of each and every puppy, talk to
the breeder. I know that each and every puppy has been nurtured at our home. I spend
HOURS every day with every puppy playing, grooming, holding, walking, and taking pictures.
When you have a question about a puppy's personality, tendencies, color, and background,
all you have to do is ask!  
Some people have always grown up with female dogs and have said when buying a puppy
always get a girl. With personal experience, I have found that girls are not always the pick of
the litter. They can also have a tendency to be harder to potty-train or "leak". With the proper
training, this can be fixed before it becomes a problem. We have had people with their heart
set on a specific puppy and leave with a different selection. Color and personality can change
your mind when you least expect it. Males can also be a handful. They have their tendencies
as well. As long as you introduce them properly to things they will come in contact with, any
dog should be great.  I have had a lot of questions like, "what is better with kids?" Really,
males and females are great with families. It can make a difference when you introduce them
to kids, other animals, crowds, and different surroundings.  This can be done by taking them
to parks, picnics, parades, baseball games and even your local Petsmart.
So when wondering...do I want a girl or a boy? Check the quality of the puppy (markings,
conformation, breeding, and personality). A good puppy with never act scared and whimper
with timidity. Check how they interact with your family and have the personality that you
WANT. Also, if looking for a show prospect, check the registry and breed standards for the
competitions that you wish to compete. Some classes and registries only allow certain colors
and have marking standards (sables cannot compete in AKC conformation shows but can
compete in agility, etc).
If looking for a potential breeding dog, check for conformation, size, and colors in their
backgrounds (if you do not like a certain color, you have to check to see how prevalent that
color is in that particular dogs' background before you breed).