I have some scenarios for Dirtside on my website (
http://home.comcast.net/~kudby).  The basic ideas could be ported over for Epic use, most likely, substituting Epic point values for my company MTOEs.
If you start to break down missions into categories, it can give you a starting point to build a scenario from:
Offensive missions:•  Movement to contact (two forces meet each other while traveling)
•  Deliberate ambush (a prepared force lies in wait to attack a traveling force)
•  Hasty ambush (a force takes up ambush positions after contact with lead elements but before the enemy's main body is in the battle area)
•  Sieze and hold an objective
•  Destroy an objective
•  Interdict an enemy force (keep them from moving off your table edge, or cause them to withdraw)
•  Assassination (one force is trying specifically to kill an enemy leader)
Defensive missions:• Deliberate defense (a prepared force, dug in and behind obstacles, defends against an attacker)
• Hasty defense (a force in a defensive posture but without the benefit of fighting positions and obstacles)
• Defend a specific objective
• Zone defense (defending forces move about freely but aren't trying to capture ground;  their aim is to prevent the other side from capturing ground)
• Break contact (a force at a disadvantage seeks to withdraw with as many of its assets intact as possible)
• Covered withdrawal (a force attacks another in order to allow friendly forces, such as civilians or supply trains, to withdraw)
• Regroup (Dispersed forces try to consolidate into a single coherent force)
In addition to scenario ideas, you can often break up the monotony of a standard scenario by adding interesting terrain;  put a river across the battlefield that is too deep to ford, and then add just two bridges.  This becomes even more interesting if one side has grav vehicles!  Or, try adding a "touchy" objective, such as a gas refinery that will blow up and obliterate anything within 30cm if it takes too much damage.  You can conduct a night battle by turning the lights off and giving each player a glow stick for the lighting.
Another idea to mix things up is to have imbalanced point values with restricted troop types.  For instance, one side has 3000 points and the other has 1800, but the larger force isn't allowed to have aircraft or artillery.  Suddenly the pucker factor begins to ramp up for that player!  You can give only one side a Titan and restrict the number of TK or MW weapons the opposing side can have;  or, one side can only take War Machines and infantry.  You can have one side be purely on foot or purely mechanized. ÂÂ
Some historical battles can give you inspiration there;  the invasion of Poland in 1939 featured horse cavalry versus armor and mech infantry.  The Battle of Leyte Gulf pitted American escort carriers and a gaggle of aircraft against a full Japanese task force.  History is full of examples of mismatched forces clashing in battle, sometimes with surprising results.
There's lots of ways to inject creativity to the typical "Tournament" scenario, but you have to be willing to let go of the concept that both sides are evenly matched and accept that each side may have specific advantages over the other.
