Hi there, I have two sets of twins and feel like I'm almost an expert on twin prams! I know you don't like the side by sides, but some do fit through shop aisles!
With my first set I had an Aussie Baby side-by-side which was great, easy to push etc but a bit too wide. I also had a double (one in front of the other) pram but to be honest it was heavy and useless, especially the baby bit at the back it was barely long enough for a newborn to lie in let alone a few months old. Plus the seat at front for a toddler doesn't recline enough so they can't lie flat.
For the second set I bought a Love N Care side by side and it is the same width as many of the 3 wheelers. I have no trouble negotiating shop aisles with this 3 wheeler.... I've seen them at Toys R Us for about $399 It is an excellent pram and has individual hoods, good baskets, pockets are back, etc, etc, etc.
The McLaren Twin Traveller is also good, it's more like a heavy duty umbrella stroller but both seats recline & it has shades, baskets, etc. i think Childcare make a similar product.
Another option is a Sit and Stand Pram (can't remeber who makes it) - my girlfriend swears by it.
Or you could just have a normal pram and a toddler seat, or you could have a normal pram and a kiddy board or skate board on the back.........
One tip: make sure if you're getting a twin pram that it fits in your boot!