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.