Help with packing for staying at multiple hotels for 2 week trip

I would use a two bag system, each.
One which is the luggage that goes in the plane.
The other a light bag which is big enough to keep several of your packing cubes.
Ideally it should have a zipper to completely close it and fold away very small. Travel stores often sell them as emergency or shopping foldable bags.

First stop after renting your car you split the cubes in his and hers, and into 'needed every stop'and 'needed rarely ever'.
Put the bigger category in the bag which is easier to open out.
With fewer cubes and more space to move them around you will find life easier.
When you 'pack' before leaving a hotel you just chuck them whatever way in the bag, no need to be careful as you have enough space.

When at a hotel where you deem it safe enough you could leave all but your 'needed every day' set in the car, but two relatively light bags are easy enough to carry.

Your last stop before you hand in your car you re-pack your cubes in your flight luggage again.

Be sure not to fill your space with souvenirs if you can not take more luggage on the plane.

Unless you are severely constrained by space, any trip two weeks or less are the easiest to pack for. Considering you have a car, space should not be much of a problem. Also you are going to generally warm and hot places which means you need fewer layers of clothes and lighter ones.

Easiest way I would think is to pack two suitcases (or duffle bags) with one week of clothes in each. Instead of the usual one suitcase per person, put in each suitcase/bag, the same number of days worth of clothes this each person. Incidentally, this saves us once when a suitcase got lost since all of us had some clothes when we landed (we learned this from a bad experience previously).

The pack an additional cosmetics bags (handbag, backpack or tote or whatever) which has what you need every day (toothbrush, toothpaste, sunscreen, etc). If you are flying to your destination you can place that bag entire in the suitcase but when you are between places, always leave it out. That way, each time you open your trunk, you grab the cosmetics and one suitcase only. Each suitcase should have a laundry bag in it where you put your dirty stuff after changing into some of the clean clothes from the same suitcase.

Should you need a jacket, leave it unpacked during the trip, just put it into the trunk directly, so that you don't have to access whichever suitcase has the jacket.

For efficient access, don't pack all the same type of stuff together. Instead pack things into outfits in, more or less, the order you intend to use them. For example, I usually where pants/shorts twice and tops once, so I pile up groups of two tops, two undies, two pairs of socks and one pants. That makes it rare for me to need to dig into the suitcase much.

Last summer we did an 8 hotel trip too put it was 3 weeks, so we packed 12 days of clothes and did a laundry in the middle but the strategy was the same. We had several one-night-stays where we found it to be very useful not to unpack everything each time. Just open the suitcase and grab the top items for each of us and we were set.

We did a 5 week trip, with the longest in any one hotel 4 nights. The number one thing to do is bring less stuff. There are two ways to achieve this:

• plan to do laundry partway through the trip
• wear some things twice before washing them

Obviously underwear and socks are not eligible for this. But pants, skirts, and shorts can be worn twice or even three times with a fresh shirt and no-one will be the wiser.

If you keep all the "bathroom and evening" stuff in just one of your bags, then after a few days you can put dirty laundry in the other one and leave it in the car. Just bring in an empty packing cube, small lightweight purse-sized "shopping bag" or the like, and when you undress put the dirty laundry in it. When you leave a hotel, at the car pause and move the dirty laundry into the bag that stays in the car.

After a week, use a laundromat. (Find one in advance on the internet so you are sure the town has one, or the hotel has machines.) Then just start the process over again.

Packing cubes will help you get more into each suitcase, and feel more organized. They can also save you from having to really unpack. Just put that cube of "socks and underwear" into the underwear drawer, and that cube of "shirts" into the closet on the sweater shelf. You can get what you want from the cube when you are dressing.

We traveled through Mexico by bus, from hotel to hotel, and also flew in by plane.

What worked for us: One large and one small backpack (approx. 50 and 15 litres, depending on what you can carry). The smaller one is for what you need during a day trip and for what you want to always carry with you^*.

The small backpack never leaves your sight.
The larger one you can leave at the hotel.

Advantages:

• You can carry it all in one go (into and out of the hotels)
• The weight is always on your back, your hands are free most of the time

Disadvantage:

• Less space than your suggested packing cubes, or suitcases. But that's the main factor anyway: if you want to take a lot with you, you're making it more difficult for yourself.

Do not forget the possibility of sending stuff home (to a neighbor?) during your trip. If you like to buy souvenirs or other local stuff, it accumulates. Going to the post office and sending things home lightens your load.
(Alternatively, but that won't apply in Utah: give stuff away. When I visited Nepal we donated lots of our clothes etc. in the last days to make room for souvenirs).

You already bought your packing cubes, limiting your options. I suggest returning them or giving them away if you consider backpacks. Do not compromise on using the best solution.

^{* During the flight to your first destination that also means essentials 'in case your backpack gets lost', e.g. some underwear and an extra T-shirt. And pack some clothes of your partner in your backpack and vice versa.}