I just got a used ultralight and I really like it. My oldest is only a little over 2 and he likes to sit on the little bench seat. My youngest is a year and sits in the front seat. I've never used the ultralight with the carseat attachment. I like that it is not huge and it is very easy to handle.
Neither, but I greatly dislike sit n stands and front back doubles (like the Graco Quattro) in general. I've used them, glad they were borrowed. I just didn't like how they maneuvered compared to other strollers (but that's my personal preference). With a four year old you might not get much use out of the jump seat. I'd get a decent single and a buggy board.
Joovy Ultralight hands down! That thing was the best money I ever spent, I was so sad to sell it when my son got too big for the back seat. In my opinion, no other sit n stand compares to the Joovy. I had a fisher price one and the baby trend (bought used on craigslist and they were AWFUL! So heavy and hard to maneuver. The joovy was SO much better!
Re: Baby Trend Sit & Stand vs. Joovy Caboose Ultralight Tandem Strollers
Neither, but I greatly dislike sit n stands and front back doubles (like the Graco Quattro) in general. I've used them, glad they were borrowed. I just didn't like how they maneuvered compared to other strollers (but that's my personal preference). With a four year old you might not get much use out of the jump seat. I'd get a decent single and a buggy board.