(further information and links are in the Health faqs as well).
Vaccinations -- whether to give them, andf if so, how, how often and whether to give boosters -- have become a hot topic in recent years with many veterinary schools now recommending dogs only need puppy vaccinations, the first annual booster, then at MOST vaccines every THREE years. In some cases researchers believe a single initial booster will protect a dog (or cat) for life against a disease. To make things even more confusing for the pet owner, there is also clear evidence that annual vaccinations can actually weaken the immune system and in themselves, can cause serious health problems.
Although many of the leading vet schools in the US now recommend a three year vax schedule, veterinarians, kennels, pet insurance companies annd groomers generally require evidence of annual vaccinations still, leaving many pet owners in a quandary.
While not offering any definitive answers, this link provides an excellent overview of the evidence, the issues, the published research, the existing recommendations and the options. I strongly advise reading through this and deciding what is best yourself given your own situation.
Be aware that you will almost certainly encounter opposition from your vet to vaccinating to any other than a yearly schedule, as annual vaccinations are very much a part of an ingrained vax system STILL pushed by the vax companies themselves, and also, are part of the 'annual visit' regime that vets would like to maintain (it is of course a good idea to take an animal for an annual check-up; linking the visit to a 'required' vax has been a useful way of getting clients to make that annual visit). Younger vets who have been schooled following the later protocols or holistic vets are likely to be more supportive.
My own choice? Right now I am observing a three-year cycle for my dogs and cats. I may move to trying titers to determine if they even need those. Given that humans do not need annual booster shots over a lifetime, I do not understand on the existing evidence, why animals should.
More info on Dr Jean Dodd's vax recommendations and doing titers (note: most would consider cavaliers to be dogs that have immuno-issues and thus fall into the 'vax minimally' category):
Recommendations from UC Davis Vet School (considered one of the most authoritative vet schools worldwide). Note they too advocate THREE YEAR vaccine boosters, not annual boosters:
bumping this up as it tends to be a popular topic!