Double stroller suggestions?

Amanda • Amanda & Bobby since 6/05 married 08/12 , mommy to J-Boy, and expecting another boy at the end of March. 💙
Hi ladies! At what age did your first child not need a stroller? Our son is currently 3 and  will be 4 at the end of May. Our second son is due at the end of March. 
I'm going back and forth between getting a double stroller or just sticking with the one I have now (single). 
If I do decide to go with a double stroller, which ones do you ladies suggest?