I just recently got back from my vacation - South Central Kansas to Sedona, AZ and back (along with lots of side excursions) in my '09 Prius. 2942 miles total. Overall, I got a solid 43.5MPG on the whole trip. Factors - I simply ran at posted speed limits (and sometimes a bit over), with cruise control on almost all the time (a few times I kicked it off going uphill). It was generally cold (down to 25F at night and about 50-55F during the day. First day we went through a snow squall in the TX panhandle, and had approx 30MPH headwinds (mileage sucked). On the way back, bucked headwinds again in the OK panhandle through KS - again, 30-35MPH headwinds. At one point (somewhere on the journey), we were doing 80MPH, with 65.6MPG indicated (had a tailwind that time, approx 20MPH). Went to the south rim of the Grand Canyon, down a day to Phoenix, spent a day or two in Jerome and Cottonwood, and lots of side excursions in and around Sedona. Overall, quite happy with performance and handling.
