City Select by Baby jogger is awesome for a tandem as it comes with a lot of seating options of positions . But we are in the same boat and went for the bugaboo donkey when we need it for longer days out and a single pram with a buggy board with a seat that actually has a harness and all for shorter popping out times
Someone I know had this pram for similar aged children as you and I don’t think they had any issues. I’ve opted for the same pram I’m currently using with a buggy board for shorter distances and then a mountain buggy duet (preloved) for longer distances/days out for my 2 year old & newborn
I swear by the Cybex gazelle s