Lots of strange, "out there" questions, but I will bite.
There is nothing wrong with how the Samurai handles up to around 70mph, although they are more suitable to cruising around 60mph. If you plan to drive faster, then I would look at a different, car-like vehicle for fast highway driving. As far as rollovers, I've been driving a Samurai for nearly 30 years now, and I have never rolled one. It is all about knowing your vehicle, and risk management.
The Sidekick is more highway friendly than a Samurai, but it is still a relatively crude vehicle by modern standards. Also, in my humble opinion when compared to the Samurai, the Sidekick makes compromises in favor of street performance over offroad ruggedness and ground clearance. (I do own/drive a Sidekick.) I do not think it is possible to exchange the front end sheetmetal between the Samurai and Sidekick as they are completely different vehicles.
If you want something heaving and wider, then I would suggest looking at a newer Jeep. The are considerably wider and longer than a Samurai, and that makes their handling more forgiving in terms or rollovers. However, they are not known for their good highway driving manners either. One cannot simply bend or break basic laws of physics.