traveling from St. louis to Lake Powell the week after labor day. We will be pulling our boat(8900 lbs) with 2007 Titan. Planning on taking I40 to flagstaff then 89 to Page. Looking for any advice on the diffilclty of hills on I40 after Amarillo especially 89 out of flagstaff. Also any interesting places to stop along the way. Plan on 4 days out, 10 days around lake powell, no set time for drive back.