A lot depends on what you really need and what direction you want to head.
Various plugins like Curviloft from Fredo6, Extrusion tools by Tig, Soapskin and bubble will all do what you need, but you may need to fiddle them a bit to get the results you want.
My personal go to for something like that would be SUbD, but it is not free and has a bit of a steep learning curve. However once you understand it it can be indispensable, depending on your work of course.
In this example you can see how just changing the edges in the corners changes the finished shape significantly.
[image: NVCatR6.gif]