Thanks for the feedback on the Chariot, SadieKate and TrekHawk. We have the bike attachment, the regular stroller attachment (so we can go places on the bike and then detach it and use it as a stroller), and the jogger attachment, although I might return that one to REI because we just bought a smaller 3-wheel stroller that has a locking front wheel, and that might be enough for my sad attempts at running.

What I want is the attachment that allows me to harness up a dog to the Chariot and let him pull her up hills. That'd be awesome.

The only drawback to the Chariot that I can see so far is that it is really big -- even the single doesn't fold down very well, so we have to remove one of the seats in our car and then there is no room for anything else. Also it has limitations as a stroller because of its size, and because it puts Penny right at the level of strange dogs and mean geese. She rides a bit higher in our other stroller.

There is a bag on the back that could hold some groceries. Probably not the full $130 shopping trips I've been doing with our other stroller, alas, but I don't think any other stroller is going to handle that sort of madness.