The most important consideration about a boarding your dogs is the facility they will be in. Some are great, some are horrible, most are in between. I personally prefer larger boarding kennels where that's a primary focus instead of boarding at smaller vets where they have a few runs and it's kind of an afterthought. (I trust my vet and know that Dallas would be safe if I boarded him there -- I just don't think he would get as much personal attention). The kennel I use is associated with a vet so emergency care is always available, but the two are run separately. There is a separate, full staff dedicated to the boarded dogs. The kennel provides raised sleeping cots, it's indoors with heat/air conditioning, dogs are walked several times a day, they will feed your own food (extra fee, but that's typical). In addition to the routine care, which is pretty good, they also allow you to purchase "extras" -- play time, swimming in the pool, nature walks, etc. These extras give your dog one-on-one time with a staff member.
Of course our dogs would rather be at home with us, but that's not always possible. A good boarding kennel is a great option -- just shop carefully.