I know a couple women in our village who've had twins over the past couple of years. Several have Phil & Ted's pushchairs, but I think it's generally down to our terrain and space more than anything else. One of the more recent ones has the
iCandy Pear. It looks quite versatile and can use carseats, prams and then be converted to seats for the kiddies. She's handled it really well with some of the narrow footpaths in our village and the terrain without difficulty.
I know it's more expensive, but it's pretty easy to customise it to your needs more than other pushchairs by the look of it.
Have you tried looking at the TwinsUK website's
store? They have Tandems and Double buggies to give you an idea where to start. Also you might want to check out the other
Multiple Birth websites - they'll help with finding pushchairs that are more friendly from birth onwards, as well as other general support and advice.
Good luck finding a pushchair that you'll be happy with!
ETA: Was just having a look at Kiddicare.com in their sale (ends in 6 days) and they have a whole selection of
Twin Pushchairs both side by side and tandem.