What you can take along, should be packed up, but consider the luggage weight. Before our trip we spoke with some people who had been traveling in the USA and thus got some tips.
Especially things like flashlight, clothesline, tablecloth, grill lighter, candles, tape, cord, all-purpose knife and our sleeping bags were very useful for us. The sleeping bags proved to be very useful in regions where it became quite cold at night since the blankets we had were very thin.
We also took along enough cosmetics because in the States even tooth paste is quite expensive.
A combinated tool, if you can smuggle it through the security checks at the airport, is very helpful. We had a Leatherman with us which served us very well.
Concerning the clothes you should take along something of everything. We had temperatures ranging from 0°C in the morning in Mesa Verde up to 47°C in the Sierra Nevada in May and June. Itīs the best to wear several layers of clothes which you can take on or off as you like.
Good shoes were enormously important for our trip because of the high demands of walking. We had good trekking shoes with us and thus perfect equipment in our opinion.
A basecap, sun glasses and sun cream were very important in that heat. Especially in the canyons one often underestimates the effects of the sun. And a severe sun burn is not a joking matter.
We also had mosquito repellent (Autan) with us but we did not need it. Somehow there were no mosquitoes at that time.
Technical equipment: with all the sights a must, in order to store memories. Our equipment: two cameras, one video camera and binoculars. Take along films and video tapes in sufficient quantities. The quality in America is not as good as in Germany, in particular with color films. We divided our cameras into one for taking pictures during the day and one for taking pictures at night.
For the intensity of the colors we recommend a polarization filter.
Because of the different time zones we would advise to check the watches when crossing state borders. California has got the summer time, Arizona does not, Utah and Nevada again have it. Then Arizona and Utah are also situated in a different time zone (Mountain Time), whereas in California and Nevada the Pacific Time applies.
And to top it all, in a large Navajo reservation (Monument Valley) which is situated within Arizona the summer time applies again because this area already belongs to Utah, although the border is actually not yet crossed there. Thatīs quite problematic and we also had our problems with the time zones. More about it in our travel report.
In the first place there is still the good old travel guide.
Basis of our preparations and also for many others was the book "Through the West of the USA" by Hans-R. Grundmann.
Here one finds useful, comprehensive and practical information. The publication "California-Southwest" by Horst Schmidt-Brümmer, which was given to us by our tour operator Dertour, was rather unsuitable and so we only took along one travel guide.
For our detailed planning the Internet turned out to be very helpful.
This is basically sufficient. However, the exact maps of the AAA pleased us very well. Using them was very simple because they showed all roads and the exact miles.
Since the AAA is the counterpart of the ADAC in the USA and both associations cooperate, one also gets these maps free of charge on demand in Germany.
If there are no more maps available in Germany, you can go to one of the numerous AAA-offices in the U.S. as well. You only have to proof that you are a member of the ADAC in order to get the desired material free of charge.
The AAA-card "Show Your Card & Save", which you only have to show, is very helpful for it. You can get this card from the ADAC, either by internet or simply at one of the offices.
national parks offer very informative material, occasionally also in German. The visitor centers in the national parks were also for us always the first point of interest before we discovered the park.
At these centers you can, for example, watch a slide show, get information about what the weather will be the next days, information about the times of sunrise and sunset and ranger programmes. Apart from the facts we already knew from the internet, these information were absolutely sufficient for our planning of the days in the national parks.
Americans are very communicative people who we found particularly in the parks very helpful and friendly.
We were quite lucky when we made our reservation in January. By a prereservation we got the most favorable flex-rate and thus the lowest price level with El Monte before it went up two days later.
If possible, you should always book the motorhome a size bigger than usual. We had booked a RV with four sleeping places and we even got one with five sleeping places.
Additionally you must book the basic equipment, the so-called convenience kit (contains tableware, cutlery, bed sheets and blankets, cleaning equipment a.o.),
as well as mile-packages and the absolutely necessary VIP-insurance (Vacation Interruption Protection). We had the possibility to book an all-inclusive package. This proved to be quite useful since we drove approx. 500 miles more than planned.
Without the package we would have had to pay extra expensively for these miles. Additionally we could use the generator without a limit.
The comfort usually says something for the private campgrounds: water and electricity directly at the RV, sufficient showers, telephones, occasionally a swimming pool (we never used one) and sometimes a dinner which could be reserved. However, all that has got its price.
Depending on the area we payed between $13 and $46 per night. The cake took San Francisco with $46. However, the average price for a RV is approx. $20 - $25 per night.
the largest private provider of campgrounds. We used a KOA campground only once since we found the fees too high.
Our search in advance was limited to the information in the internet on the homepage of the 
Gathering wood is actually almost always forbidden. However, we could also not resist to gather some wood occasionally for our campfire evenings. You may buy fire wood but it costs quite much.
numbers and directions. Nevertheless, you should not take a wrong way because that can sometimes mean an additional way of many miles.
The condition of the roads leaves sometimes much to be desired. The highways in and around L.A. were the worst. Non-asphalted roads you should avoid if possible since you donīt have any insurance protection for the RV on those roads. Due to the size and width of the country there is not much traffic, except for the large cities. That guarantees relatively stress-free driving.
Parking lots are in general plentifully available and sufficiently large, only in the big cities it is not always very easy to find a parking space with a RV.
Itīs the cheapest when you buy the chainsī own brands and make use of the special offers.
But watch out, many special offers are only for customers with a customer or member card. We easily got one for Safeway by giving a fantasy address in the USA. For the first grocery shopping you should plan a lot of time. It took us two hours - despite shopping list!
We had even written our shopping list a few days before our flight in order to see which things we can still take with us from Germany.
Here thereīs to say that phoning by so-called prepaid cards is the most favorable and cheapest. Simply rub free the pin number and there you go. The endless dialing of numbers like those of the operator, the language, the pin number and finally the actual telephone number was a bit problematic.
Once you dial a wrong number, you have to start over again. But nevertheless, we were charged for the dialing. But there are also supposed to be cards which are charged only with the beginning of the call. We usually bought our phone cards at the supermarket but once we noticed that, in our opinion, the card was only half charged.
Probably the reason was a higher price for the minute which can be calculated completely free in the USA.