Playpen/playard alternatives

[Xax]

We're having twins, so a standard-sized (tiny) playpen isn't going to be big enough (not to mention they're ridiculously overpriced). I saw a fence-like "playpen" at Babies R Us (link), and I think I might go that route. Is there a proper name for those? Does anyone have any recommendations?

[Kranberry]

We bought that, as my wife was having problems with sore back and muscle strain from holding him. So it was a way of making sure he didn't hurt himself (at 7.5 months). The problem was he was just starting to crawl, and when we put him in this pen, which I would say is around a diameter of a little over 5", he stopped crawling and just sat and played. So we returned the pen, and he started crawling like mad again. We just cordoned off his area with some well placed furniture and he's happy as can be.