Can't really offer advice on car type, but I think it's very wise that you look into getting a bigger car. Not necessarily for safety reasons (I understand them), but for space reasons. Two kids (or family of 4) and their needed items everytime you leave the house (not considering any special trips) take up a LOT of space in a car. I would especially consider it if a possible 3rd child is in the mix! We have 3 kids, we have a mini van, and there are days when I still need more room! :)
Only advice I can give on car is more related to what they can do. Remote locks because anything that takes only 1 hand is great! Sliding side doors, even if they're manual because sliding doors are (to me) easier to open with one hand and you don't have to worry about hitting another car in the process (especially if you have kids that can open the doors themselves - we do). If you allow drinks in the car and have smaller kids I'd pick a car with a darker interior carpet so that spills aren't as obvious (red Kool-aid really stands out on tan interiors)! If you have children in car seats I'd recommend a fabric seat as oppossed to leather. Leather is nice, it also tears easy (edges of carseat punctures easily and if you have to move carseat sliding it across the seat can rip it too).
Good luck with your possible upcoming "new" car purchase! :)