We are taking a trip to San Diego to see our son graduate from the Marines.We live in Illinois and we are leaving this weekend planning on making the trip in 3 days. We will be taking the south route by taking I44 and I40. My question is once we get into Arizona should we go through Flagstaff or drop down to Phoenix or maybe any other ideas. We are first time RVers and want to avoid as much of the moutains as possible. We have a Class A motorhome so we definitely need travelling experience before attempting mountain driving. Our son moved up our purchase time for the RV. Any help you could gives us would be greatly appreciated. Thank you