Deisel/Flexfuel/Gas for tow vehicle

I'll be in the market for a tow vehicle sometime soon (soon to me is typically a year away) and I'm considering diesel and flexfuel. I know there are a number of SUV's and pickups that will run on flexfuel, and there are some interesting diesel options. This has to be a daily driver as well.
My question is has anyone had experience with either of these options or done some calculating considering the difference in fuel prices and the difference in mpg?
Does the cheaper cost of flexfuel overcome the reduced fuel mileage and performance? (I've read that mpg is reduced with flexfuel and performance may not be as good.)
Does the improved fuel mileage with diesel compensate for the additional cost? (In our area diesel is over $4 and gas is around $3.40 - $3.50.)
One vehicle I'm considering is a Jeep Grand Cherokee with the CRD diesel option - it is supposed to be certified for all 50 states in 2009 and has a towing capacity of about 7500 lbs. A smaller version has been in the Jeep Liberty and I've seen that TV with a pretty good sized Chalet behind it.
I need AWD or at least 4WD so that limits the choices a little. Another possibility is a pickup - I'm wondering if Toyota will have a diesel version soon?
I know this is a diverse and knowledgeable group, so I know I should get some good info. And probably a few opinions - all welcome!
Thanks
Alan