Should I get a guinea pig?

I already have quite a few pets, Cat, Dog, Hermit , Fish.. but i just cannot seem to get enough! I LOVE animals alot and have lately been highly interested in Guinea Pigs. I know exactly how to care for them but I can't seem to make up my mind. And also, i have a large hutch and I really am unsure of where in the house I should put it, my Dog and hermit inhabit my bedroom as it is and im not sure if adding guinea pigs will over crowd it but my Dog might have to learn to sleep in her own room. My room is really big though, so space is not a problem. My parents are ok with the idea as I try hard at school but if I didn't want them so bad then they wouldn't consider it. Also if anyone has any ideas for a different material other than linolem for a substitute of corflute or the stuff for the bottom of c&c cages it would be much appreciated (i am in australia and the materials are hard to come by). Thanks for all your help :)