I use the 6'3" Retro Fish Double from Creatures of Leasure.
For everyday use I put the Nugget and a Twin Tip and don't need to remove the fins.
For travelling I prefer to remove the fins of both boards (don't need to remove the pads or straps) and use air conditioning lines insulation tubes (cut in half) around the rails and the bag close without problem. There still place to put your harness, bar and kite . When I travelled with Jet Blue they charge me the same rate they charge for Kite Equipment or for a surfboard, is the same, $50 each way. (needs to be below 50 lbs)
This is from their web page.
•10mm closed cell padding
•600 denier and heat reflective silver poly fabric
•interior fin pocket
•5mm tongue to separate boards
It also came with a shoulder strap.
The most I like from this bag is that have and internal "tongue" to separate the boards
this eliminate the possibility that one board scrach or damage the other.
This bag fit even a TT and a Sector 54 that I had.
The attach picture is of the newest bag, I think I have the 2011 bag but the size is the same.