C&C are the most versatile , I bought some grids from Costco , couldn't fathom the fastening buttons so used cable ties (make sure there's no loose ends to scratch them)
You can do levels and ramps but mine were happier on one level . They had the small bedroom (one group in C&C , one group in a big cage ) at night in winter .
You can make a lid (I did when my DBro cat visited ) I used cable ties as the hinge and a padlock to secure it (so didnt have to keep cutting the ties)
It needed to rest on something , they had some solid boxes inside .
And C&C needs lined , I used thick cardboard , made boxes for hay /hiding spaces . Layers of puppy pads , newspaper , fleece
Fleece is nice but invest in a rubber brush ( like a Buddy Brush) and a PetBag (zipped up ,) to save your washing machine . Scenr free detergent and no fabric conditioner . Pigs are respiratory sensitice . Fabric conditioner stocks fleece wicking moisture .
The rough cheap IKEA ones were good (£1.50 ish , no pesky stiching to remove either )
Guinea pigs are lovely but take up a load of space . When the hutch advice says 4'x2' for 2 piggies that is a misertly size , Those hutches you see in Petstores have a living area/sleeping area . Add the bowls etc , it isn't enough .
If you want a hutch , look at rabbit hutches , more space .
They can use a ramp for a double hutch but it takes up space and some guinea-pigs have injuries falling down them.
If you get boars , they do need more space , two of everything and any hidey houses need 2 doors so one doesn't get trapped (though my sows were feistier than our boars
)
They are very untidy
The hay smells . Guinea pigs don't smell if you keep them cllean . Ours had daily , roll up the dirty bedding and replaced . Spot clean the floor . Proper full clean (everything ) probably 5-7 days .
They need hay 24/7 unlimited . Usually recommended a lump of hay their bodysize for eating . More if they use as bedding . You can use fleece as a base and put hay in a box to sleep in. It'll get dirty .
We gave ours hay in loo roll tubes or hay cookies in summer or if we didn't want them to sleep on it . ( Hay poke eye injury or post surgery )
You might gets ones that are meh to the cat . Or they might be terrified . The rescue will lnow if they're used to household noises etc
Can I just give you a Heads Up ?
I kept guineas as a child Then when my DD was 9yo we got a boar pair and had eight piggies over a period of time .
DH wanted some cats so after the last one died (old age) we got two young cats .
Cats are (whisper it) much much easier !