I'm not going to buy a double stroller. That just seems ridiculous at this point. T. will be 3 when A. is born unless A. makes an early arrival and then it will be a temporary, technical issue.
Sit n Stand is probably the traditional solution, with Joovy Caboose as a current competitor. These are essentially the usual crappy, heavy stroller with a built in step to stand on and a "jump seat" with a 3 point harness (may or may not have padding on the seat; seat may or may not be usable if you use the main seat with a carseat adapter and car seat; may or may not be compatible with our car seat). Fisher Price _had_ an entry which, while not, technically, "recalled" is no longer being sold and let's just say there were some "issues".
The standard UK solution (also available here) is the Buggy Board, which attaches to most, but not all strollers (amazingly, will attach to the Volo! but not to the BOB). It's the step part; no jump seat. Of course, the Volo doesn't adapt to a carseat and it's not a good idea to put a really young baby in one.
A new solution is the Strolli, which is like a trail-a-trike that can attach to many strollers. Its major claimed advantage is that you won't clip your feet on it as you would the Buggy Board.
This puts us in buy yet another stroller territory, possibly including the Buggy Board (I have to say, post carseat, the Volo + Buggy Board is awesomely lightweight without kiddies and therefore hideously tempting).
Phil & Ted make a tandem not-a-jogger stroller (but it looks like one) with a carseat adapter that is compatible with our carseat. I said I wouldn't buy a double stroller; this would probably be the exception. Kinda cramped, apparently, and if you are using the carseat, the toddler can't sit in the other seat and the Buggy Board is _definitely_ not compatible.
The maker of our carseat makes a stroller that it clips into and that the Buggy Board is compatible with. The seat on the stroller, unfortunately, is small enough it is typically outgrown in the first year. It does recline, which is a plus, but you couldn't, say, strap the wee one on to sleep and let the toddler sleep in the stroller.
The MacLaren Techno XLR might be compatible with the Buggy Board, is big enough for a toddler (a big toddler at 65 lb limit! More like a 1st grader), can fit our car seat. This is pretty tempting. You could sleep both kids (one in soft carrier, other in stroller).
The MacLaren Easy Traveler would be speculative only. It might or might not be compatible with the carseat or the board, and in any event, of questionable safety once loaded that heavily. But my, what a clever little travel device. No opportunity to sleep both kids at once, since it's just a stroller frame.
Anyone out there got an opinion? Right now, I'm torn between the Britax Vigor (made by maker of our carseat) and the MacLaren Techno XLR, and the MacLaren is winning, hands down. In any event, I'll be buying the Buggy Board and possibly the Strolli, for use with whatever we get and, ultimately, the Volo as well.
ETA: FWIW, the BOB has a carseat adapter which we don't have, and which I won't buy for travel because R. does not trust airplanes not to utterly destroy the BOB in a particularly annoying way having to do with where the front wheel attaches. However, if all I want is something better to move baby-in-bucket-on-crappy-terrain, that's an option as well.