Unlike many trainers, I am not too uptight about dogs sleeping in bed with their owners. If the dog is properly house trained, and there is solid, human-centric leadership in the relationship, it should not be a problem. This means that the dog knows that being on the bed requires being invited. Even when a dog has no bed-related issues I still like to see him earn it in some way.
Creating strong leadership with your dog means controlling what the dog holds near and dear and teaching him that all good things in life are filtered through his people. Often at a training session I notice people have taught their dogs basic commands like "sit," "down" and "stay." They have utilized classes or private sessions with a trainer or a book or video to learn these techniques. The problem is that somewhere along the line the training stalled out and the dog only has to perform these behaviors to receive a treat.
Now let me be clear: using treats is a great way to teach dogs new behaviors, impulse control, focused attention, loose leash walking, etc. Treats, however, should be faded out of the equation as the dog learns what our commands mean and can respond with reliability.
Let's look at it this way: In first grade you may have gotten a gold star sticker on your homework if you did a good job. Our teachers encouraged us to work hard and enjoy learning, but once we learned and matured that was no longer necessary. By the time you get to college, you are expected to take the initiative and work hard.
So with that in mind, setting forth a strong training program, as well as practicing consistent leadership and guidance, is the root to success in your relationship with your dog. The first two years of your dog's life should be about learning how the world works -- what is appropriate for a given situation such as greeting you at the door, where to eliminate, how to walk through the neighborhood, greeting strangers and other dogs, etc.
This includes gaining access to the bed and other special resources. Simply having your dog learn to sit before being invited into bed is an important step to teaching impulse control, manners and deference to you as the leader and controller of all wonderful things in life. It also adds an element of structure and work to your dog's life, two things that he finds very important and fulfilling.
It is easy to trivialize this step, especially if your dog does not have any big behavior problems. Keep in mind, however, that being consistent with these simple steps is the equivalent to teaching your child to say "excuse me," "please" and "thank you." You wouldn't trivialize that, now would you?
So by all means, cuddle up in bed with your best friend. Just be sure he knows the rules and that the bed is human space that he must earn with a polite "Excuse me, may I please come up there with you?"
That is how you spoil your dog. Teach him how to be a dog in a human environment and what is expected of him. I find way too often dogs are being punished for rules they are not aware existed in the first place. The key to training is consistent, clear, gentle and fair guidance from the leader -- you.