My wife owns a V-Strom 650 (aka "The Wee-Strom"), I have the Multistrada 620. I had a tough time deciding as well.

Short answer:
If you want the more "practical" bike (or plan to tour a lot), you need to get the V-Strom. If the V-Strom were a car, it'd be a minivan.

If you want the more ...

I am 5'10", 180 lbs. I have been riding for 5 years. I could afford either bike.

I chose the 620. Why?

* 620 gets 50+ mpg. I can't justify buying a new bike (especially $11K+) that gets worse gas mileage than my car

* 620 is plenty powerful enough for me. Realistically, I'm not going to take it ...