A.H.
I LOVE my GRACO duo glider. I think the tandem option is best for stores and sidewalks. It has two detachable food trays. The infant car seat will attach either front or back. There is plenty of room for your 19 month old in front or back, I tested several strollers with my then 3 year old when I was pregnant and this one was the best fit for her. The back seat fully reclines which is great so when your infant is old enough she can sleep or play while you shop or take walks. It's a bit heavier than the single stroller we had, but I can still easily lift it into the back of our Highlander. Also, the catch and release features are very easy to operate.
I think all Graco infant seats will fit this stroller, but not sure about other brands, you'll have to ask a sales person on that one.