Peter,
Regarding the bed lengths in an Eriba - there are at least two lengths available - and I'll take our Eriba Triton 410 as an example:
In the "rear" of the Triton, there are two standard sized 6ft6 single beds which can also be made up as a 6ft6 by 6ft6 "square" King size bed. We have ours as two singles, then you can walk between them to the end locker.
Alternatively, you can buy the 410 (as the 418) with a double bed at the end - 5ft by 6ft6 - and you sleep across the van. If you don't know, it looks like that bed is short, but it's just turned through a right angle. This has a larger front dinette, but isn't as popular.
We bought a Triton 410 because we can leave the two single beds down all the time, and use the front dinette to eat, read, listen to music, etc.
Interior:
The Eriba is made from a cage of welded tubular steel tubing - so most people are surprised by the amount of usable space inside - there's no need for big lumps of chipboard to support the upper lockers and cupboards - they are bolted to the tubular steel frame.
This tubular steel frame is expensive to make, it has an impact on how the caravan is assembled, and consequently an Eriba is more expensive than you would expect - but excellent resale values and long life more than compensate.
The Eriba is probably the only caravan that is made how most people think a caravan is made - the frame is welded together, the aluminium body panels are fitted, the insulation and wall panels are fitted, and then the lockers, cooker, fridge are bolted to the walls. A UK caravan is made from the floor up - and the walls are screwed on last of all - much cheaper to make, but flawed from a strength and water ingress point of view.
Comfort and facilities:
Seating and bedding is either multi-density foam or sprung interior foam - on a slatted wood base. The original owner will have chosen from four pages of close typed options, or in the UK taken the easy way out and bought one of the factory packages.
The seating cushions (beds) are flat - no rolled edges - which means that the bed is perfectly flat and a great sleep. Firmer than UK caravan beds - I'd describe them as "orthopaedic" - and no buttons or other embellishments to get in the way of a good night's sleep.
Toilet / Washroom:
Depending on model, you can opt for just a toilet (which we did - and stay on serviced sites) or a toilet / washroom.
Cooking / heating:
Standard is a three burner gas hob, 3-way fridge and blown air Truma S3002 heating. A fitted oven is not an option - most Eriba owners will use a Remoska (the standard model from Lakeland).
The blown air trunking runs inside the caravan - making them especially good in the winter.
Insulation:
Rated for use down to -18