I see that you are interested in getting a 2 line family plan with 2 new devices! First I am going to provide you with a link that shows you all of the available family plans up for comparison on the WhistleOut website!
Click this link to see all of the 2 line plan options: WhistleOut: 2 Line Family Plans
Now, since you are also interested in purchasing new devices, I have provided another search engine results link. In the next search results link, I have shown you all of your available options when purchasing a new iPhone 5s and similar devices!
Click this link to see iPhone 5s plans and similar devices: WhistleOut Search Engine iPhone 5s/Similar devices
From both search results pages, I have provided the links to the carriers I feel would be most beneficial to you!