I recently came across a book, Garden Rooms: Create and Decorate Outdoor Garden Spaces (Time-Life; 1999), by Catriona Tudor Erler. It has some great ideas and lovely photos. I especially loved the big pots and sundial on columns. (The sundial is actually on the capitol of a column. I have a sundial on an old birdbath base; and I use old birdbath bases laid on their sides for interest in the beds.)
Garden rooms or patios can have floors made of brick, gravel, concrete, stone, tile, etc. (I have a brick patio and a stone patio laid on concrete. Sometimes I wish I'd left the concrete plain; it would be more level, but we'd collected a lot of beautiful stones.) There's also wood decking, which I avoid because of maintenance. You can use composite materials instead, but I've learned that they can melt if you drop something from the grill on them. You can make garden paths from those materials too, also mulch, though that will have to be replenished, and it's uneven.
Water features are lovely and soothing--except for the maintenance and predators eating your fish. The book has a number of ponds, including big pots, and, of course, fountains. I loved the horizontal millstone covered with moss. That's one I hadn't seen before. There's also an vertical millstone that's setting inside something or else they've sawed off its bottom, which would be a shame. The horizontal millstone is much prettier as a fountain.
The book includes garden structures (I love Thomas Jefferson's pavilion on the edge of a terrace) and lighting. There are types of lights and lighting of plants: uplighting, moonlighting (downlighting), shadowing (light in front), and silhouetting (light behind a plant). You need simple, open plants or trees for this to be effective.
The author also looks at birdbaths (I have one that's a recreation of a dinosaur footprint, btw; I got it at Historic Bok Sanctuary) and topiary. I love the example of the fox hunt scene from Ladew Topiary Gardens in Monkton, Maryland.
I really enjoyed this book; it has references and an index at the end, which is alway helpful. (I wouldn't have had to look through the whole book again to find that sundial if I'd known that!)