Over vaccination is a fairly common thing these days it seems like.... I base it off of the individual dogs lifestyle. Rabies is a no brainier, it's required by law! Bordatella is either an intranasal or injectable vaccine that protects against kennel cough- (do you have your dog groomed at a groomers? Is he a regular doggy day care attendee? Regular dog park visitor?). Leptospirosis is transmitted through urine- (Do you use your dog for hunting? Is he a regular swimmer in lakes, ponds, etc?) Distemper affects a few body systems and is usually fatal, I would definitely vaccinate against this one. Parvo virus is also typically fatal and affects mainly puppies and is transmitted through the feces of infected animals. Parainfluenza is an upper respiratory disease and is very contagious and often seen in areas with a large dog population (groomers, dog shows, dog festivals, racing tracks, even pet stores).

I hope this helps you but I would take a look at your dog's lifestyle with your veterinarian and you should then be able to come up with a good vaccination plan!