Cheaper Indian Sandstone is not always the bargain it appears as it is thinner, or poorer quality and more porous causing leaching of the minerals in the mortar onto the top surface of the stone. There are some inexpensive granite slabs currently available that make a wonderful surface only slightly more expensive than Indian Sandstone. The more expensive options are Travertine, York stone, Basalt, and Marble.
The choice of screening will depend on available budget. Walls are expensive to build, wooden screens with posts and trellis panels are much cheaper. Planting a hedge is usually the cheapest option, but may take a while to grow in unless you can afford large plants or an instant hedge.
Polished concrete makes a wonderful contemporary surface for the patio. Resin bound gravel is not only great for driveways, but makes an excellent contribution to the patio paving when combined with other materials for textural contrast. Get the best quality stone you can afford then the patio will last longer and stay looking good for many years. A patio should never be designed in isolation without considering the rest of the garden. A well designed garden where all the elements are in scale with each other and the house will connect the house and garden. A balanced design that includes a patio or multiple patios will give the garden coherence and ensure that it is a pleasant, comfortable space in which to spend time.
Consider the long term practically and maintenance of patio materials carefully....Most people only think about materials in terms of the cost but that should not be your only consideration. You don't always require the cheapest patio material. On the contrary, you also need to think about what patio materials are going to last for a long time and what kind of maintenance each type of material needs.