This is our setup at home. When we got Beemer I felt that one playpen just wasn't big enough for both of them. I took this picture on my "nanny cam" just a few minutes ago.
It's the older version of this one.
Amazon.com: Pet Gear Home 'N Go Pet Pen with... We've bought the new ones but use them only for traveling. They do have a zip on lid. The old one doesn't.
We love our setup. I never really close the doors. When we come home we just pull them apart. They go in there on their own all the time. You might note the bungee cord holding them together. When we replaced our carpet with hardwood it didn't take Beemer any time to figure out that he could work them apart and squeeze out. When we travel we take either one or both of them - depending on where we're going and how long we'll be there.
When I told my breeder that I used a playpen she was concerned about the floor. She said that the elevated floors like you see in human playpens aren't good for a dogs leg development if they stay in there a lot. These are designed for dogs and the bottom rests on the floor. Mine mostly just sleep when they're in it though so I'm not sure it would be a big deal if it was elevated.