We have a Schwinn SC925 Safari Double Baby Jogging Stroller. The front weel swivels (or optionally locks), which makes it easy to push and turn one-handed. It folds down easily. Lots of storage underneath.

Where will you be traveling? Most airports and places that cater to kids can easily accommodate double strollers, but some places can't. We had a tough time in NY and would have rather had two umbrella strollers (although that wouldn't work for you with 2 riders and just 1 adult). Some international locations might have tight spots, too.