Are guinea pigs affectionate?

I've been tempted to get two guinea pigs as pets (two because I read they are happier with a friend). I had one when I was a child but I'm pretty sure we didn't take care of him properly. He had a wire cage and we never gave him hay, which I read is a big part of their diets.

My question to any guinea pig owners is, are they affectionate? Do they play with you and have fun? I don't have much experience with rodents so I don't even really know how you would play with a guinea pig. Also, are they ever really potty trained or do they just kind of go whenever and wherever?

Guinea pigs do best in a group of two or more. You are right to get two of them at once.
It is known that they are very responsive to your feeding and handling. If you treat them well and bond with them, yes they can play with you but not the kind of playing a dog can offer. You first need a large cage. More room will make them more active. You also need to take them out of the cage and give them lots of floor time, it can make them more sociable.

Give them some toys can help too.

My daughter has 4. They are great furry affectionate animals. They love to be held, carried and snuggled. She carries them around in her pocket all the time. They never try to escape, jump down or hide. They sit with her when she reads or watches tv. They coo like doves, at least I think that's what it sounds like, when they are happy and secure. Little Sassy, Yeti, Specks and Cheese coo all the time.

Yes! They are very affectionate. We have two now. One was really skittish and would be terrified when we held him. It's been fun to see him warm up and now be able to hang out on one of the kid's lap and get a treat. When I pick him up he clings to me for dear life. It is adorable. I haven't had any success litter training, but you can set up a kitchen area with their food, and you will find they go there the most. Also, keep one of the corners of the cage dark with a towel hanging over it or something, and they will naturally like that spot the best. It makes it easier to clean that way.