Both of my dogs are boarded at least once a year and Jack goes TONS of places where he comes into contact with strange dogs at least twice a week right now--the dog park, the training center where he swims, pet stores, the training center where he does rally--so we do get the required vacs for all that. I do heartworm pills every 30 days or so year round--not worth the risk not to IMHO. I don't however, do flea and tick treatments unless I actually see a flea or tick on one of the dogs, which seems to be rare for some reason--maybe they don't like blood full of unnecessary chemicals
From what I read about the dog flu when I googled it the disease does not seem extremely severe or fatal, so I likely won't bother. I did get myself the flu shot though and have for the last several years and am happy to report that I have not become paralyzed to date. I work with horses and figure that I am far more likely to sustain paralyzing in injury from that than from one shot a year that I have shown no reaction to so far.