Hi, ooohh new guinea-pigs 
The run needs to be very secure- make sure it cannot be lifted (we have a large Bunny Business run. Metal, folds up for storage, we peg it down with tent pegs)
Make sure the ground is level where the sides are, no spaces they can squeeze out (or something can squeeze in)
Go as big as you can , and move the run round to get fresh grass (GP droppings make good fertilisers)
Check the lawn for weeds that are toxic - mainly buttercups and daisies, bulb plants.
Depending on what size of pigs you get, check the bar spaces (Lardy adults won't fit through but tiny piggies might)
They don't dig so they don't need a mesh on the base (and shouldn't have anything mesh/grid to walk on anyway, their paws are delicate)
They will "Popcorn" so they need a bit of height but not as much as rabbits . You'll need to give them a safe housie in the run.
Foxes,cats,hovering birds of prey are all potential foe (and things like escaped ferrets)
The run needs a roof unless you plan to sit right next to them (there are lots of 'soft top' runs with netting roofs but theyy wouldn't protect them)
And you need a gymnast (luckily for me , my DD is one 
) to get into the run to catch the little blighters.
Pictures of the piggies are compulsary