Although I'm only 3 months into this (I can't believe it's been 3 months already!), we've finally figured out what works and what doesn't for us. First, I LOVE the Double Snap n Go (SNG) stroller. I use it all the time when it's just me and the twins going somewhere. It is nearly impossible to carry 2 infant seat carriers and a diaper bag without either a second person to help or the SNG stroller.
I also love the Moby Wrap. In the beginning I could fit both twins in there but now I can only get one wrapped up comfortably. But it has been a God-Send. Truly, there have been days that I would have been lost without it.
We already had a lot of hand-me-down stuff from our first 2 babies. But I"ve found that one of the twins likes bouncy seats and the other doesn't. Both of them love the taller swings, not the take-along swings. I've also found that they won't sleep in the Pack n plays AT ALL. So, I think you might consider registering for one of each of the big things and trying out both the twins in them before you decide to get a second. Also, I've found that their preferences change over time. They slept in the packnplay fine in the very beginning. Now they hate it. If you have a friend with babies or small children, maybe they'll let you try out their equipment before you buy.
Oh, and I'd DEFINITELY register for the Graco Sweetpeace swing. It is pricey but it has saved my sanity. It is truly wonderful.
" I object to violence because when it appears to do good, the good is only temporary; the evil it does is permanent." Mahatma Gandhi
"This is the ultimate weakness of violence: It multiplies evil and violence in the universe. It doesn't solve any problems." Martin Luther King, Jr.