You could return the 6 you got your wife before the 14 days are up and get both of your phones using next which will bring down the cost to $15 per line instead of $40. Assuming you got the 64gb 6 for both and used next 18 for both, your payment would be $62 for both. Since you would be saving $25 a line this route, your bill would go up only $12 a month...plus you get to save the amount you have to pay upfront to upgrade them for a 2 year contract which for the 6 64gb would be $530 for both ($650 - 120 taxes which are due when you get the phones).
Your bill this way would be $130 for the 30gb data, $30 for both iPhone and $62 for both next payments minus the 24% discount which would come off the $130 only so brings that part down to $99 so your total bill would be $191 plus tax. Tax would only be charged on the $99 and the $30. The next payments don't have tax on them since you already would have paid it when you got the phones. If you do it the 2 year contract way, your bill would Be $149 a month plus tax. You would have to pay $630 up front for both phones(assuming you get the 6 64gb for both). Good luck.
Thanks for breaking it down for me. That was extremely helpful.