My DD will be 2 and 5 months when bubs comes along. I bought one of those adventure buggies. I haven't used it much with toddler seat yet just practise turns but seems to be quite good. I liked it cause its different from others the toddler seat sits up on the handle bars so when both are old enough to sit up no ones view will be blocked by another.
I bought it off e-bay too alot cheaper that way.