M.K.
I actually loved my Graco DuoGlider. It was perfect for me and my kids aged 14 months apart. I had no problems with the weight of the stroller (which was my greatest fear) or the folding -- it was easy to get in and out of the minivan. But the best part was the HUGE storage area. I could fit a golf umbrella in the storage area, in addition to over-stuffed large diaper bag, 2 coats, insulated lunch pack (snacks and drinks) and my medium-sized purse. Plus, it wasn't that expensive.
There was no way I was buying a sit-and-stand when my kids were that young. As soon as your daughter realizes that the older child is allowed to walk/ride whenever he wants, you'll never be able to keep her in the stroller again. Strap them both in and make it a non-issue!
Too bad you don't live closer...I'm ready to get rid of mine. :)
Good luck no matter what you pick!