I would ask around at pet stores, groomers, dog parks etc and get some recommendations. I would also make a list of ones in the phone book. Many kennels have websites now. You can google them and see what comes up. Also, make a list of questions, and call and ask the individual kennels. Once you've narrowed it down, visit your favorites. They should let you see the kennel area- make sure it is clean, the dogs are fed, etc.
Growing up my family used a very typical kennel- its basically a row of cages with indoor/outdoor runs and the dogs stay in the run until you come to pick them up, being fed and having the run cleaned, but not much else. There was a grooming shop attached and they would bath your dog for extra if you wished. Toys and bedding from home was discouraged. Some kennels even don't want you to bring your own food!
However, in many places you know have choices in boarding kennels. They make nice, high end boarding facilities with state of the art "suites" that are just like their own little bedroom, daily playgroups, and extras like massage or personal walks, or streaming video so you can check in on vacation. In my area, which is not particularly large, we have 3 or 4 such facilities.
My dog stayed at one the last time I went away. She had a "suite" which is like a room with a door she can see out of. I brought her own bed, her favorite toy, treats and food prebagged with her supplements. I toured the place before I made an appointment- they showed me all the kennels as well as the play yards, and told me about the daily schedule. The kennels were clean, the dogs looked happy, and the staff was knowledgeable. While I was away, my dog had daily supervised play time with the other dogs of her size and temperament. I chose not to have her bathed before pick up (although it was an option) so she came home a bit dirty (it was out in the country, they had big outdoor play yards) but exhausted and VERY happy. The staff was able to tell me everything she had been up too. I was very pleased, and will use them again.
So your questions- she loves it, she's still thrilled to see me when i returned, but tuckered out for a few days, and no, my family has been boarding dogs for years and have never had an issue with illness, injury, or fleas. I do notify my vet that I am boarding and they are authorized to treat her, the kennel has my vets info and also an emergency number where I can be reached if she needed treatment.
I don't think I'd ever go back to the cage-style kenneling. I think in some places- like some vets offices its worse- the dogs are basically crated all day with a walk or two. then you have kennel runs, and then you have boarding facilities that actively spend time with your dog for a significant portion of the day. The cost was not that much more expensive compred to traditional kennel boarding.