nearly there...3 weeks to go! Yippee....started thinking about packing and suddenly thought....how cold does it get overnight at Zion, Monument Valley and the Grand Canyon? OR for that matter....how hot does it get during the day.......!!!! Gosh....what to pack...my big thick jumper or my not so skinny swim top!!!any advice much appreciated to stop me from bringing all but the kitchen sink! Thank you! PS we are stopping on the South Rim in an RV!