Dog Daycares are very helpful. We have two 9yr old labs that are fine by themselves....we also have a 10 month old Lab that loves his exercise!! So we have found daycares along the way, always look them up for reviews if you use them. Last one we used, our little guy came home totally exhausted...met another Lab his age and they did their best to wear each other out...they succeeded. That was one very quiet night!
I would hesitate to use dog walkers, mainly because I don't want to give my keys to someone I don't know.
Enjoy your travels.