I wish they were making the 6x18 when we bought ours (even though that one is not through LIvin Lite). It's not much more weight, and my husband likes the width being no wider than our tow vehicle. I think I could have talked him into 6x18 -- and that would give me enough room to have that floor-to-ceiling cabinet I so desperately want!!!
The combo bathroom on the 6x15 -- I do dry it off after everyone takes their shower, so we're not walking into a wet area to go to the bathroom. But, I consider that to be a very minor inconvenience. It IS a tight space, but none of us are very big, even my husband. If you were a big or tall person that shower would be a big pain in the butt. But for us, space is a premium and I'd rather use the space for other purposes.