Cooler for multi-day car camping

Yetis are ridiculously expensive, and they have managed to brand themselves as a lifestyle statement, which I find annoying. But their coolers are pretty amazing, and probably hard to beat. I left mine (one of the smaller sizes) in the car in the full sun in New Mexico during a backpacking trip and came back to cold beer 5 days later. For the application you're describing, a smaller Yeti (maybe a Roadie 20 at $250?) might be worth the investment. If you freeze your steaks, dogs, etc before loading them in the cooler, they'll probably keep an extra day or so.

Keep in mind what cools the interior goods is what you put in it. Maybe go with what you've got. One possible approach (though maybe not with children) is layer wet ice or cold packs (if you want some stuff cold but not frozen, ironically the wet ice will act as a bit of insulation) over some slabs of dry ice with maybe the longer termed food placed frozen between the dry and wet ice/cold packs. Even "cheap" coolers will stay cold using that setup. I shipped every biological specimen we had across the country in fifty styrofoam 48 L coolers packed with dry ice: didn't lose a thing. Plus I learned each aircraft has a one ton limit of dry ice per load: which we just met.

the-iceman.com/dry-ice/dry-ice-calculator/

www.continentalcarbonic.com/cmss_files/attachmentlibrary/Dry%20Ice%20Frozen%20Food%20Packing%20Chart%209-13-12.pdf

Starts at $2 per pound, a lot cheaper than a $400 cooler!.
www.continentalcarbonic.com/faqs.html

Mixing wet and dry ice:
dryiceinfo.com

We have one of those Igloo MaxCold ones, too, but the "cube" style. I prefer that shape because a smaller footprint means less drowned food. My strategy is to always start with 2 frozen gallon water bottles (we always have them ready to go in our chest freezer.) Prefer that to buying block ice as the melted water stays in the container. Also found out on a week-long float trip that covering the top with a wet folded towel really increases the insulation. A full cooler also stays cooler.

Yes for personal cold but not frozen things I use milk jugs and some coffee cans filled with water that being smaller work well for day trip needs in my smaller cooler.

We use a basic Coleman ice chest for our trips. Starting out with a block of ice (I freeze a container that's maybe just over a gallon?), it usually lasts for 2-3 days on our trips (usually pretty hot weather). I do try to keep a duffel or so on top for extra insulation. Once that original ice is gone, I buy cube ice, even when block ice is available, not because it works as well--it doesn't--but because I got tired of the mess. We put the cubes in the container that used to be ice, so that our ice chest doesn't end up a sloppy wet mess. Whatever is in the bag from the store and doesn't fit in the container, goes in our water bottles (which may also go in the ice chest if there's room) or down peoples' necks.

In March, the spouse and I went to Death Valley, and did 5 nights without resupply. The ice lasted for about 4.5 of those, and things stayed cool enough even after that (with cool water) to be okay for stuff like yogurt and cheese. I think even the milk made it to the last morning. The big difference with where you are, though, is that it always cooled off at night, so we didn't have so much melting around the clock.

Start off with as much food frozen as possible, to increase the amount of "ice" you have, and to give it farther to go to spoiling temps. When we are all 4 traveling, we have to buy more food every 2-3 days anyway, so buying more ice isn't a burden.