Of course, being avid runners and walkers, we had to have a running stroller. We have only good things to say about the Bob Revolution running stroller. It's great for running and walking and going to the zoo, the park, the mall...we love it. The little section in the front where the child's feet go is ideal for my toddler to sit (while my infant sits in the stroller) on a quick walk to and from the park. Can't say enough about this stroller. The swivel front wheel is ideal for changing from walking to running and back (and easily does so). My sister has the Bob with the fixed front wheel and she doesn't like it as much.
Note: The Bugaboo double stroller is still in the works...don't think I haven't been in contact with them quite a bit!!
Upon having my second child, well, actually several months before (out of excitement) we purchased an Urban Double Mountain Buggy. Talk about a smooth ride! It is deemed the narrowest side-by-side double stroller out there, as it fits through doorways (why buy a stroller that doesn't??). My one issue with it is the seats don't sit up completely upright...thus my son tends to throw a fit! I like how the seats do lay back to almost a complete recline position. I purchased the sun cover, which is great for protecting them from the brightness, but I don't think they like it...my daughter says she wants it off so she can "see out better." So, we lube up with sunscreen and wear hats and sunglasses! It is a great stroller, folding up quite easily and compactly. Its wheels can also lock in place or swivel, so it's a nice option for running and walking. It's a great zoo stroller too! I just can't wait until my son is less picky about his "ride" and will sit for extended periods in strollers. This is definitely one that will go on lots of power walks. I had my daughter and her friend side by side in the Mountain Buggy and it was super easy to push—they fit comfortably. When we take our nightly walks and my son says no thank you to the stroller (man is he getting heavy for the Bjorn...the Hug-a-Bub is still comfortable though), the second empty seat of the Mountain Buggy makes a great baby doll seat!
