Having played a number of battles (ancients, Napoleonic and one or two other periods) the main element that has struck me is the lack of the element of suprise. Although FOG (and other rules) allows for ambushes and flank marches etc., without a referee these are pretty difficult to pull off - especially as your opponent will notice that you have a number of bases you've yet to place on the table!
This is most true of historical battle re-enactments (where everyone knows who is turning up, where and when).
Yet historically, suprise was often a key determinant of victory, such as Frederick the Great marching the bulk of his troops round the side of a large hill - hidden from view - while he feinted an attack the other way. The opposition knew nothing of the flank attack until it arrived and secured victory. But try replicating that in a wargame situation. Even moving a marker around will alert the opponent to something coming their way and they will re-deploy accordingly.
In Principles of War there is the use of movement bases - some of which are dummies, which have to be spotted to reveal what they actually comprise of - but simply meant that a quick shuffle of troops took place before the lines met.
But when you can see the entire battlefield laid out with all the troops on display, it does take away any
So I'm going to look into adding some house rules for my favourite rule sets to see if we can generate a bit of suprise (such as only identifying troops when they get within a scale of 1/2 a mile or less (for example) which will make delployment more fun) and working harder on making flank attacks, ambushes and 'secret' moves more effective.