Everyone has great ideas!
I believe that the room needs to be true to its environment. A room in New Mexico may have clay tiles on floor, stucco walls and a rustic iron bed. A room on the beach can do sea gulls, white, slipcovered furniture and a white picket fence headboard. Our home is in the mountains, so we have pine walls, stone floors, and rustic furnishings.
But, please, everything in the room should have a purpose. Once, I had a guest take an artistic photograph of the snow shoes I had left beside the door. It wasn’t décor, I had just come in from doing a chore in the deep snow! I have stayed in an Amish style B&B where it took an extra five minutes to clear the bed of all the faceless dolls. I stayed in one guest room with a huge bouquet of roses in the room. While fumbling in the dark, trying to find a lamp, I knocked the vase over. It was a fiasco. Water in the luggage and all. Art on the wall is fine for warming up a room. Books on local history and activities add a touch of character. A warm lap quilt draped over the arm of a chair can add that pop of color. But be sure everything has a purpose!
The number one priority has to be the bed. Great linens, smooth and pristine white is our favorite. Plush comforters in as large a size as is appropriate. I use queen sized feather comforter on our twin beds. Can't tell you how many guests comment on the bedding! Pass on the cutesy pillows (I know, sacrilege for some) but be generous with a selection of sleeping pillows. (We try to provide 2 standards & one king per guest)
A place to sit is a must in my opinion. An armchair per guest if you can! It is nice to sit in your room and relax, watching TV or reading a book. I love using slip covers, so they can be laundered when soiled. (I also wash them seasonally) Drape a cozy afghan or lap quilt, if appropriate.
Many of my guests seem to appreciate the TV trays and the luggage stands.
A jar of snacks also gets positive comments from my guests. I put a box of raisins, bag of peanuts, granola bar, rice crispy bar and some small candies in a glass jar. People who have been traveling until late into the night, have found these invaluable.
I also have individual Keurig coffee makers in each room.
Traveling ourselves is the best way to find what makes a good room great! Get out there and visit other Air BnB's!