it depends on your Ds's weight.
i've just bought a mothers choice (its an '07 one...but meh) as most prams weights for the toddler seat is 15kg. if you need a longer lasting pram the side by side ones are good (most go to 22kg per side. or in mountain buggy itd 25kg a side). Valco make a good roomy one for two kids. what ever you do - try out differant prams! i wanted a tadom one until i pushed two around a shop floor.