"Worth it" depends on whether you want it. If you wanted 16" wheels, then buying a Touring is the least expensive way to get them. You get a few other things with the touring:
16" wheels with slightly better quality tires.
Slightly stiffer shocks.
Slightly stiffer antisway bars.
Larger rear spoiler.
The packages are different in the touring. It may be you can only get pkg #6 in the touring, in fact. In which case it's a lot more expensive if you don't want all that extra stuff.

You will have to make up your own mind if it's "worth it". Test drive each model to see if you can tell the differences. If you're not a handling nut then the standard model is probably just fine. I'm a handling nut and I find the standard model works just fine. Bonus, the 15" tires are cheaper when you wear them out!

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)