I've made some simple 2 D graphics in windows forms to display a hex grid and units counters. I'd got to a similar point on the UI using C++ and Directx11, before I decided to abandon the code and switch to C#, so I'm happy to switch again for a better long term solution.

I'm trying to make a simple scenario/ world editor for a turn based strategy game. However I want to make the map area scrollable and combine it with other controls for data entry/display. I could do it by using multiple forms, but that feels messy, so I was thinking of gong over to WPF. I think, I'm finally starting to get to grips with WPF. Its supposed to have a steep learning curve. This seems mainly due to Microsoft's irritating habit of desgning everything around the complete novice and hiding everything but the flashy interface away. Meaning you waste loads of time as soon as you want / need to know what's actually going on. What the justification for hiding the 'main' function away is in a development tool beats me.

Anyway any thoughts. I'm using C# so the options seem to be Forms, WPF or XNA. I understand integrating graphics and controls in XNA is even more difficult. Is this correct?

Although I cannot provide a solution to your problem at the moment, I can say that I recently visited a similar debate about WinForms in my project. First, there are more options for GUI libraries. For instance look at Mono's discussion of different cross platform options. My project discounted WPF on the bases of many community threads on the subject indicated that WPF could not exist outside a Microsoft environment. Perhaps you feel that your product should only be developed for MS-Windows, but my philosophy is to keep my efforts operating in as standard an environment as possible so as to expand my abilities to adapt to future contingencies.

On a technical side, there is no reason that C# and WinForms wouldn't be able to handle the problem as you stated. Also, so long as you are talking about using image tiles and not a pseudo modeled tile method, I would guess the using direct draw or opengl will not be as efficient as winforms, but that's just a guess and far beyond my ability to quantify.