The cabin interior can run the gamut from a dark and north-woods aesthetic to something contemporary and bright. A sleeping loft or two flanking a larger communal space is usually all that's necessary. And keep the finishes durable and low maintenance. Materials such as wood boards on the walls and ceilings will allow you to enjoy the place with a minimum of fuss.
And try an attractive, clean-burning woodstove if you don't want a fireplace. A stove placed in the middle of the space will be just about all that's needed to heat the entire cabin.