I am working on ideas for the first expansion for History Dad, but I am trying to decide which way to go.

The original plan was to focus on a theme, such as a specific unit, campaign or battle and then do some material to fit that such as scenarios, a couple of unique units and so forth.

However I am wondering if maybe it would be better to just do a spread of different things in the expansion instead. (So perhaps there's a bit of Eastern Front and a bit of Normandy and so on). 

The former is more thematic of course and may get people interested in a new topic, but then, it may also discourage people who are not interested in that. With the latter option we can cover a wider range of stuff, but the risk of course is that it will be more thinly spread out.

A middle ground may be to have a smaller theme in the expansion (f.x. a section on Polish vehicles) and then accompany that with a variety of scenarios. 

Decisions decisions.