I'm sorta in the same boat.. Have unlimited data.. We have 2 phones, use 2-3GB /month..

Curious if it's better to buy 2 Phones at full retail keeping unlimited data plan we have now..

OR...

Get the discount on both phones and the 2GB data plan and just pay the $10, overages, we figure we'd be hitting 4-5 GB about 50% of the time..... 

The math gets complicated, and I don't know what the future holds..