1) Well, SMAC has excellent value. The forum on this site will direct you to a number of excellent sceanrios/additional factions/add-ons.
2) Panzer General 2 is worth its weight in gold. It is a classic turn-based WWII wargame. I have the game and it still plays well, especially with all the add-ons being made by a dedicated group of gamers.
There is a ton of new campaigns/scenarios/new equipment files/units, etc.
A starting point would be to check out the following sites:
a) for campaigns, scenarios:
http://www.wargamer.com/pg2campaigns/
b) huge forum focussing on PG2, PG, and other wargames:
http://pub88.ezboard.com/bjpspanzers
3) Axis & Allies - yes beer & pretzel wargame. But it is a nice diversion, and I still play it occasionally.
4) Army men - That game doesn't appeal to me at all.
So, the two best games would be SMAC and PG2 - it works out to be $10.00 each - an excellent bargain in MHO.