Don't get a dog at a pet store whatever you do, supporting the puppy mill industry is pretty disgusting imo - I'd say if you have any reservations about getting a dog, especially with the travel, I'd hold off for a little while. Its a pretty big decision. We have 2 dogs and I also travel quite a bit, ideally we usually have someone watch the house and dogs for us when we go out of town. This works out really good and the dogs seem to prefer that to boarding.
If you do board the dog, find a good place. Here in LA there are several places that i'd recommend but none are 25 bucks a day, most run in the area of 80-100 bucks per day and those are the only places I'd feel comfortable leaving my dog if I was going to travel as much as you. These places are cage free kennels where the dogs are outside most of the day and sleep in little casitas with other dogs etc.
The places that charge 25 bucks a day usually leave the dogs in crates/kennels all day and only take them out briefly for exercise. If you are going to do this 4 months out of the year, why bother getting a dog.
If you still have your heart set on getting a dog and a small one at that, I'd rec'd getting a Brussels Griffon. They are pretty cool dogs and make great, loyal pets.
You may remember the dog from as good as it gets, that was a BG. The great thing about getting a griffon is you can rescue one here;
http://www.brusselsgriffonrescue.org/
Give that site a look, there are a bunch of dogs that are in need of good homes and its a way better way to go than getting a dog from a petstore. If you don't know what a puppy mill is, google it.
How cute is this one here;
http://www.brusselsgriffonrescue.org...l08-28-07.html
Haralabob