I have a Skip Hop Versa and love it, but I'm not sure you will have enough room if you have 2 in diapers. The Skip Hop Studio Tote would probably be a better choice. I wonder if the Columbia Trekster backpack would work for you, as you could have both hands free. Or maybe the JJB Be Spicy. I have heard that the new patterns/fabrics are lighter than the older ones. Then there is always the Skip Hop Duo, but that might be TOO large.
Also, believe it or not, the new carters and gerber totes are very nice looking, and VERY large. So if designer/non designer isn't important to you, you might want to look at those.
Mom to a spirited, red-headed, former 28-weeker 10/2009 and a more mellow monkey 12/2013.