I totally recommend the freedom of doing it “sans-tour group”. Grab a couple friends and make your own tour. There’s enough resources online to help plan it out.
That area gets tens of thousands of tourists a day (not an exaggeration). And despite the outrageous terrain and distance, they’ve made it very easy to get around. There are tons and tons of taxi cabs and they’re almost all new and in good shape. The drivers are courteous and friendly as they’ve got plenty of competition and their living is predicated on tourists. I had a great time talking to my driver and he was super kind and patient with my laowaihua.
I went in the spring, and it was pretty simple. Flew into the airport and took a cab from the airport to HuangLong and then to the little town of JiuZhaiGou (this was very long, but kind of the only option). I don’t remember what the rate was, but it’s a fixed rate to do this – ask someone inside of the airport before talking to the cabs, just to be safe.
The drive is beautiful. there’s a 4000 meter pass that you go over from the airport to HuangLong, and then you’ll go back over it on the way to JiuZhaiGou. JZG is at a lower elevation, so you’ll see some different landscapes as you head there. Lots of yaks and prayer flags.
Pro-tip. There’s tons and tons of boardwalk that is unused in JZG park and you can find yourself in relative solitude while staying on official, legal boardwalk paths. For some very nuanced cultural reasons, the nai nais in matching floral prints are only interested in going and taking all the same pictures that their friends show off at the majiang table from their trip they took last year and are keen to beat you with their selfie stick if you interfere with that by just being around. SO to avoid that, just go where they dont. When you get off a bus and they all walk down hill, walk up hill and go around to the otherside of whatever lake you find yourself at. you’ll be totally by yourself.