Can't go wrong with a 686. Very popular, decent quality, decent trigger. Some (including myself) prefer the pre-lock models. The much older ones, if you can find a nice one, are a little nicer "fit and finish" - and a nice one usually goes for similar money as a new one.
While dry firing a centre fire piece, rarely does any harm, a lot of guys wouldn't be comfortable with it - so if you want to try out the "trigger break" in SA, in the store, stick your thumb between the frame and the hammer, after you've cocked it. You will get a feel for how the trigger breaks, without the hammer hitting the frame. In DA, just ride the hammer spur with your "off" thumb - you'l be able to feel how it cycles, without the hammer hitting the frame. - Or buy some snap caps. Once it's your gun - you can dry fire it all you want, if that's your choice.