Hellobee Boards

I’d stick to the double — mainly for the storage underneath (groceries etc)

Or a really solid single with standing board for the older LO

We moved to the surburbs but can still walk places. I plan to keep the big, sturdy stroller until my youngest is 3 yo

My kids are 3.5 and 5.5 and I would still take our stroller if we had a really big walking day ahead of us. We got rid of our bigger inline double stroller about 2 years ago when one seat broke and we bought a chicco Bravo-for-2, which has a cool built in ride-on-board for your older kid plus s fold down jump seat in the back.

The push is not near as good as the expensive strollers especially as your kids get older and weigh more. But you can fold it with al the parts attached (unlike the aftermarket ride-on boards or little jump seats), so that part is clutch. Plus, where we live, the stroller is as much for all the stuff as it is for the kids—the snacks and water bottles and bags and gear and groceries.

My kids are 4.5 and 12mo, so my older son was 3.5 when the baby was born. My big boy pretty much stopped using a stroller at 3. Also in a city where all we do is walk (school is almost a mile and we walk both ways).
I kept our big uppababy for the baby and got a ride-on board for the big kid. He can honestly walk anywhere at this point but if I have both of them with me I prefer for him to be on the board because then I can walk at my own pace.
If I were you I would get a stroller with a board option (citymini has one). If your 3.5yo isn’t huge like mine, you could also get the ride-on attachment for the yo-yo. I’m obsessed with the yo-yo and just got it for this baby and it’s lived up to all the hype. If my 4.5yo wasn’t a beast I would have gotten rid of the UB Vista by now and just kept the yo-yo.

We will move to the burbs this summer and I will likely get rid of the uppababy then and just keep our yo-yo and maybe buy another less expensive umbrella.

I'm in a city too and have a 4 year old and 1 year old. The 4 year old isn't completely out of the stroller depending on the activity. We walk almost everywhere; the ride on board is a lifesaver. She even rides in the seat sometimes and I wear the baby if we are having an exceptionally bad day.
We have a city select lux with a ride on board and a bench seat. I really liked the bench seat because it has a 3 point harness. In crowds or really long walks she gets an actual seat that fits her and the baby still has his seat. Its a beast to push though. But more often we use the riding board. Don't cheap out if you go this route though. You could pick up a used vista or city select; bugaboo makes a great board but their seats are on the smaller size so you might not get as much use as the other two.
We also have a thule urban glide; they can both smash in to the seat tandem style but the baby hates that now. Some kids can ride in the footwell of a Bob but again, its not a permanent solution.

I live in nyc. My kids are 4 and 2.5. We never really used a double stroller regularly. It's been the Cruz with a boogie board until before Christmas. now we use the maclaren plus scooter or bike or walking. Or two kids on scooters (which is madness). Both kids are good walkers and I think they walk several miles a day plus park play. My 4year old is huge and doesn't really fit in the stroller or on the boogie board anymore. I never liked a double stroller, but we had a double umbrella when they were little for long outings. We also has a city select double which was just a plain and wet never used it. We ar often out all day and they do just fine.