Hi Chuck, all of the 25' models of this era have the bathroom in the rear. Ours has the mid-double bed, which is a drop-down sofa. We put in a double mattress for comfort. The only drawback to this is the aisle to the bathroom is narrower when the bed is down permanently - but that's OK with us.
There is a accordion-type partition between the double bed and the kitchen/dinette - which also makes into a double bed. Lots of pictures with various models can be found at
Vintage Airstream Home in the "Vintage Archives" section.
I think in ours the dinette was Airstream-built, but put in sometime later after the front sofa was removed. The woodgrain and trim match perfectly, so I don't think it was a DIY job. Factory dinettes are
really rare.
As for your choice - it depends on how big you want to go. There are just 2 of us so 25' is plenty of room.
Kevin