I also say Phil & Teds. We've been using ours since Jack was a newborn. It is great with the two boys. If you want the baby to lie down when he/she is older, just move the toddler seat to the front again and undo the zips and clips - you'll go back to having one lying and one sitting in a few seconds.

WRT to car seats, we did exactly the same thing. We got the maxi rider and it's great. When they are older and need the harness you can get an anti-submarine clip too which makes them so much safer (stops them sliding down - when they are still using the straps that come with the seat it doesn't matter as they already have the bit between the legs).

Our boys were supposed to be 20 months apart but now are 19 months due to Tom's early arrival!