I'm a big fan of the WWII small-scale skirmish theme (detailed enough, but without too much minutia), so I stick to the nationality rules and don't do any "anything goes" builds.
A few house rules/play preferences I have are:
-commanders can serve as spotters, but can't battle or move during assault phase if spotting (presumes he has a radio man, and frees up points if you don't want to pack a spotter in lower point games)
-my friends and I don't use planes (I have A20 for air battles
Other than that, I pretty much stick to the original rule set. It fits a nice niche in my game collection in that it is detailed enough to enjoy the theme without being bogged by excessive detail.
+1 on historical play, I think those are fun, too. But then, I am a history teacher, so my opinion frequently swings historical (my students light up when I bring in pieces for class examples, haha).
The idea of "Power Builds" is an interesting one... Now I'm intrigued about a dodgeball-style pick: select a few types of units and do a draft pick match. Panzergrenadiers, Japanese Bicycles, and Shermans vs. SE Paras, Cossacks, and Panthers, anyone?