Neaten up the slab by edging it with the edger after mowing the area. You may have to run the edger around a couple times to deal with the encroaching grass. Put the portable grill away. Try putting two chairs and a tiny bistro table in one corner- use things you already have or buy on July 4th sales (in US). You can add an umbrella, too.

How about a nice flowering vine for the cyclone fence?

The grills are a bit rusted....how about painting all three a consistent color, such as dark bronze, using paint designed for heat resistance? http://www.doityourself.com/stry/how-to-paint-a-bbq-grill#b

A simple wooden DIY table could add work surface and unify the area. You may have spare lumber that can be used. It's outdoors so construction and finish can be very rustic. http://www.instructables.com/id/BBQ-table-made-from-pallets/ I would scale it generously and include hooks for utensils.