Some general ideas that make keeps beauuuuuuuuuutiful:
Black goza "wall to wall" carpeting in selected areas to create contrast
Plants, plants, and more plants!
Special touches people have done:
"Area rugs" - created from gozas and items such as bedrolls, as well as the new heritage add-on rugs
Indoor gardens (the new heritage trees and rubble are fabulous for this) with fountains (heritage or custom crafted from items)
Banners or lighting above the front doors (requires patience and stacking of items to raise stuff up the required height)
"Creeping" vines (on interior walls)
Creative flooring elements - you can use game boards, gems, gozas, etc. to make interesting designs
Curtains (constructed out of items or the new heritage collection ones) to create areas of interest.
I liked this northwest corner treatment in one of Larisa's keeps with the SE wall hangings (dojo stealables) and the potted plant on the crafted armoire:
Here is the laboratory in one of Sarsmi's keeps:
An attractive roof treatment by lubertdas(?) posted in another thread by hyggeligt (using the new heritage ladders makes this so much easier than the "old" method of creating goza stairs to the top!):
Great corner treatments using gozas (from Sarsmi)
Retlaw of Vesper's tasteful dining area, and extensive use of vines
Here are some of my custom houses - most of these elements were created with items and "add ons" and will work in a keep. I particularly like making little cozy groupings with the low tables, gozas, and pillows. And remember, that you can put add-ons together, such as the beds, and armoires, to give different, new looks.
Rope curtains, which do not block movement, and would look nice around areas of a keep, especially if you have large paintings in an alcove or something, to make it look museum-ish.
Here is a little kitchen I made in a friend's keep:
I suggest you look at
these wonderful tutorials, to get ideas for special little deco touches. Myself and many others have used these core themes to create new designs. Creativity seems to fuel creativity.
And...saving for last, note how many of these absolutely fabulous design elements are featured in MissEcho's castle:
http://members.westnet.com.au/hjs_echo/pics/castlepage.html
Decorating a keep or castle can seem overwhelming because of the size. Don't feel that you must finish it quickly or that you can't work on individual areas, and deck them out to your heart's content, while ignoring entire sections of the structure. Eventually, you will probably decide on a cohesive theme, and you can adjust as needed.
Have fun!
-Skylark