I have seen many posts on this list with pups that are challenging. I often recommend dog training classes. They offer so much more than most people know. I think EVERY dog and their owner should attend at the minimum of one basic obedience class. If you purchase a pup I think a puppy kindergarten class and basic obedience class is in order.
ENVIRONMENTAL SOCIALIZATION - Obedience classes give your dog the opportunity to be in a different environment with different smells, noises and distractions. This gives your dog the exposure he needs to learn to be comfortable in different environments.
DOG SOCIALIZATION - this gives your dog/pup the ability to be around other dogs in a more controlled environment to learn how to appropriately interact with other dogs.
HUMAN SOCIALIZATION - This is a wonderful opportunity for your pup/dog to learn to meet new folks of all different ages, shapes and sizes. Remember your dog will probably meet many people in its lifetime and the more comfortable it is with people the better he will enjoy going with you.
BONDING - Training offers a wonderful bonding time set aside for just you and your dog. This becomes a special outing where your focus is totally on your dog and not the normal routine of your home environment.
DOG RULES - Classes offer training to help you learn the most basic of rules that all dogs should know. Sit, down, stay and come are the most important. These classes teach you how to teach your dog and how to incorporate all of these rules in to a daily routine to help your dog become a good companion.
DOGS BODY LANGUAGE - Many classes will discuss with you the body language of dogs and how to try to understand what they are trying to project to you by different behaviors. I think many people would be much better trainers and owners understanding how a dog reacts and learn some of how they think.
HOUSE TRAINING - Many trainers can explain how dogs are housebroken and what you can expect. I have been amazed at the posts I have seen from folks that even consider a pup can be trained as young as 9 or 10 weeks old. This will not happen. Physically dogs are unable to control their elimintations at this young age. They have also not lived long enough to learn the process to communicate with you that they need to go outside. Realistically I would not consider a dog remotely trained until they are about a year old. Yes, they can hold it for longer periods and dont have accidents as frequently but you can bet it is a rare dog that is solid until they are at least a year.
SURRENDERING DOGS - Did you know that near 85% of the reason dogs are in shelters is because of behavior? You can bet most of these dogs were not born this way but were not trained by their owners. Sadly as they grow and are no longer the cute pup they brought home people are not willing to tolerate the behaviors as they grow up. Many dogs have destructive or fearful behaviors because their owners did not get involved enough with their training to help them become good companions. One only need to contact a rescue or visit your local shelter to see many animals that fit this description.
CRATE TRAINING - This is a wonderful tool to train dogs but one must learn the appropriate times to crate a dog. It is best not used for punishment as many people choose to use it. Dogs should eat in their crate, get a treat each time they enter to help them learn this is a good and safe place to be. Many classes will spend part of a lesson explaining this.
GROOMING AND HANDLING TOLERANCE - Dogs need to be groomed regularly as well as to have their body handled in all ways. Good grooming, nail trimming and brushing teeth are all things that a pups should learn early on. I have seen countless posts of dogs over reacting to their humans with handling.
RESPECT - dog training classes dogs will learn to offer respect to their owners and teach you how to gain it from your dog. Dogs should not be growling and snapping at people that come near their food or treats. You should be able to remove something from your dogs mouth at any time no matter what it happens to be. Most training classes will teach you this and the importance of it.
In summation I think training classes are a wonderful tool to help you learn more about your dog and how to be a good dog owner. Many of the problems I see mentioned on this list have to do with lack of knowledge training dogs. You have invested in purchasing a pup, vaccines, supplies why not invest a bit of time and money in training to help you raise a dog that is a joy to live with.