Boars are lovely and very affectionate (we've had 4 boars and 4 sows over a period of 7 years, we know have one sow left , she''ll be 5yo in May)
We've had C&C grids , good because you can adapt the shape and size. Also got a 4'x2' cage with a plastic base and metal bar top.
You could look in places like Jolleys for a rabbit cage which is bigger.
Plastic is easier to clean than wood , and guineas need a lot of cleaning 
All one level is preferred , the ramps on some of those double decker cages are so steep and take up quite a lot of space.
Our original boar pair ( 1yo brothers) had a wooen playhouse adapted by DH. It was 6'62 x 6'6" so loads of floor space, houses, hay bed.
2 boars do well together if they bond and establish who is alpha. They may well squabble a bit (the Terrible Teens) but you can pre-empt and prevent a lot , mainly with space for them.
If you have tiny piglets you might need to overlap C&C grids . They need lined , pigs can't walk on grids.
We use fleece on puppy pads and newspaper , with a box of hay for sleeping in.
If you use fleece , buy a couple of the pet bedding bags and some unscented detergent . I put the liquid in the bag, wash them and hang them out, the hay blows away . Saves my machine 
Have you got pigs lined up?