Mario your torn between the V6 and the 4 right? I drive both, almost every day. (I own two - 2001 V6 solara and V6 2002 camry, and i work on a fleet that has I4 Camry).
You do highway driving, so the mileage penalty will not be much. I love the power of the V6 and i considered very carefully before i chose it. (I drive in LA, not exactly the place to try for maximum mpg). The I4 will always give better mpg, that's why people buy them, that and the I4's are much more common and cost a little less.
With my V6, I get 25 mpg average, with stop and go being 70% of my driving. Open road, the mpg goes up, way up. My wife and i took the V6 Solara last year to Grand Canyon and back (500 miles) and mostly at 80 mph. 28 mpg.
And not for lack of meaningful conversation, mind you, she slept much of the way home

, leather seats you know. And, i think, the V6. Smooth, quiet, and assured.
If you choose the I4 i think you might get 4 or 5 more mpg, there are plenty of other posts about this if you are looking for more detailed info.