Great- a photo. How about deciding if you want seating, dining, play space, or a combination, and then work out where each function makes the most sense. You could to a lot with plants, including large trees, in pots to soften the area and to screen one area from another, or could pull up some of the pavers to make planting spaces directly into the ground. Sketch out what you might want to use the space for and where you need it, and it will come together pretty quickly. Your local nursery can be an excellent resource.

Agree with sooz001. Create "zones" or rooms using planters or garden beds. Use varying heights, the highest shrubs at the back of the space. A trellis beside the wood door would look great. You could remove some of the pavers to create a garden bed against the wall.

Love the colour and walkway.

awesome patio - agree with dividing into zones. a lounge area and a dining area. do you need any of it for kid play space? whatever you decide add lots of pot plants and maybe a small fountain. the planters should be of varying heights and colours of plants.

Is the fence around the yard wooden? I think it needs something to break up the pale and slate colours. If you get furniture with cushions get a colourful fabric. Or the planters, make them colourful with the colourful plants. A colourful umbrella for a table would help too. Good luck!