I have 2 boys--a 4 yr old and a 2 yr old. We have always used Britax carseats (after the infant carrier seat.) We have the roundabout in our smaller car-a Toyota RAV 4. I think it goes to 45 lbs. We have the marathon in our bigger car--a Volvo XC90. The marathon goes to 65 lbs. We have been extremely happy with them. We even got my mom a marathon for her car. Also, there are several places that will install your carseat for you. We went to the Park Ridge fire dept, but there are many police stations that do that too.
I also have the Peg Perego Twin Aria which I got when my second was born. I love it. I was unaware of the bad reviews. I wanted a side by side for a lot of reasons. I wanted to see both boys. It was very lightweight especially in and out of the car. It is a breeze to open and close--this is my favorite feature.
In the front to back double strollers I didn't want the boys to fight over who sat in front and I also found it very heavy to lift in and out of the car. I did a lot of research and tried a lot of side by sides. The combi was nice, but the seats seemed very small--not a lot of room for growth, particularly for my older son. It also seemed rickety. The Maclaren was nice and I almost got it, but the opening and closing of it was cumbersome and the baskets were small and hard to get to if the child was reclining. The mountain buggy was really nice but costly and not foldable for the car. The different jogging ones were great but I wasn't confident that they could fold well enough for travel in and out of the car.
The trays are on the Aria are on the small side, but at least it has trays. The boys like it for snacks. It doesn't hold sippy cups. It doesn't bother us, but I've seen attachments you can get via internet. The basket on the bottom is quite large and easy to get to even when both seats are reclined. There's a bit of a learning curve in the beginning when maneuvering in and out of narrow doors, though the stroller is the same width as a wheelchair. My husband recommends a "C" maneuver--Angle in the doorway one way and continue forward turning the opposite angle you came in.
Anyway, the last thing I can recommend is that you think about how you're going to use the stroller. That will best determine what you should get. Good luck!