Spend your $ wisely for pet vacation care
I strongly recommend using a professional sitter who is a member of a good organization such as PSI and who is bonded and insured and has several references! If you have an excellent sitter, you will return home to a clean house and happy pets. Ask the sitter to return with the key so you can see how your pet is with the sitter. Even if the sitter brings their pet with them for the duration of the job, the likelihood of your pets getting something from one dog is unlikely. Especially for multiple pets, this is usually a cheaper route.
If you do go the kennel route, be sure to ask them how often and for how long your pet will get to go outside each day, how many other dogs will be out at the same time and what is the ratio of adults to dogs for their care both inside and outside. There are good kennels out there or they wouldn't still be in business....just do your homework.
Also, I buy my Frontline on ebay and measure it out myself....there is a lot of savings there.