Hi Anne-Marie,
Wow! I have travelled with Just You 3 times and one of these times I went on the holiday you are about to embark upon. The first time I went on the shorter National Park USA trip in the month of May and this gave me a hunger for more especially to see Yellowstone, so I went back for the longer version which is the one you are going on. It was trully magnificent and every bit got better and better. The scenery was so amazing and the company great too. I went mid sept. The weather was glorious apart from the first day when it rained. Because you will be experiencing different altitudes the weather can be changeable. Up at the higher levels it can be cooler. A warm vest was my saving grace and took up no suitcase room. As you move hotels each day I travelled light and rolled my clothes. I was able to wash clothes at hotels and to be honest the sand does get into everything anyway. So my advice take few clothes and wash them while away. And don't try unpacking your case each night as this will involve so much repacking!!!
http://www.rockingvcafe.com/place.cfm You usually spend two night in Kanab and I can't recommend this restaurant highly enough. Great veggie food, and meat and salads and amazing desserts. If a few of you are going do book ahead as the locals and tourists love it and it gets busy.There is only one main street so it is easy to find.
Hot air ballooning was good fun but the helicopter over Grand canyon will be one of the most amazing things you do in your life!!! Go for it! Those who took the small jet plane from Monument valley found it disappointing. The jet being so small rocked about hugely making them feel sick and made taking photos from the plane impossible. They were all rather green when disembarking..........
We had no problems changing travellers cheques when I went but tis best to take some dollars in notes too just in case.
You will love it. It is such a great holiday and I have wonderful photos. Let me know if I can help more with your planning.