When learning the C# language. With all the applications being developed these days. Would I be better off focusing on windows forms development or WPF development. I want to develope software that uses ADO.net for SQL Server database access. Also stand alone applications to integrate with Microsoft Office to create charts and graphs etc...
I'd be using WPF as it also allows you to do Silverlight applications using the same XAML markup.
Having said that, there are horses for courses so you need to choose the appropriate tool for the job. That does mean you need to know both to make an informed decision. :)
The learning curve with WPF is definitely much steeper - at the same time you can easily whip up some simple UI in Windows Forms to fill your needs in regards to ADO.net or SQL Server database access. Once you add charts/graphs to the mix, you are going to want to learn WPF hands down though.
Also you might want to look at Lightswitch, which takes care of some of the complexity with Silverlight/WPF.
Though WPF is the future and it gives you so much flexibility, I don't recommend switching completely to WPF. Also, you will be able to make the most out of WPF if you have a designer that will be able to work on the design part. I'm not saying you need to have a designer but based on my experience with WPF, if you want to develop a killer looking application, you definitely need to have some one that knows the bits and bytes of WPF. Just as BrokenGlass said, the learning curve with WPF is too steep. So, just make a gradual switch. If you already have some Windows Form applications, try to rewrite some of those in WPF.
The kind of stuff you're trying to do can be done with both WinForms and WPF. WinForms is a more familiar paradigm but (big but) XAML in general, WPF in particular, is not the future but the current way of doing Windows UI's in .NET, WinForms being the past it is basically in maintenance mode (good for existing apps, dare I say obsolete for new apps). Yes, XAML posses a somewhat steep learning curve, but the abilities you get are worth the effort, besides there are more and more resources (books, libraries) on XAML/WPF/Silverlight while for WinForms there are plenty but stagnant (I haven't seen any new edition of a WinForms book in a couple of years). One thing worth noting is the databinding capacities of XAML which render unnecesary many of the code moving data from/to objects/datasets to/from visual controls.
Although for the purposes of Windows UI that both can achieve similar results, their function is independent of one another as is their purpose.
WinForms is tried and true, non-evolving due to strong roots. It does not mean WinForms is deprecated. It just means that the foundation classes for WinForms are well established and flexible. Keep in mind the flexibility in extending WinForms via the Control class and deep-engineering UI messaging (via handles exposed by the WinForms classes).
WPF however is an abstraction layer to design user interfaces, not necessarily or exclusively Windows user interfaces. The most difficult hurdle to leap is transitioning from the thought of coordinate based user interfaces (pixel/bitmap/index) to vector based user interfaces where WPF can adapt to virtually any size control or plane of rendering.
The benefit of WPF is that you're learning three different targets for your applications - Windows UI, SilverLight, and now Windows Phone. WinForms targets Windows UI and Windows Mobile (CE). A clean UI based on common widgets has an appropriate foundation in WinForms. If a customized, dynamic UI is your target, take WPF for a spin.
As your prime objective is to learn C# you should concentrate more on language features rather then your UI. You should try to learn and use various features of C# and what all it supports and how. Learning(C#) will be much more in developing Business layer and Data layer of your application rather then your UI; so you should concentrate on building these layers first(with any presentation framework).
I am not sure whether you have any prior experience in any of console applications, WinForms, WPF or ASP.net but for learning purpose you should pick one you are most comfortable with. In case you are starting a fresh then I would suggest you to first start with Winforms as you will be writing a lot of C# code in WinForms then in WPF.
My answer is totally focusd on fact that your prime goal is to learn C# and not on which UI framework is better etc.