EDIT: Added poll, changed first post for new readers.
My Ideas: Firstly, to increase the cost of Royal Breeding and decrease the cost of Summon Galadhrim, to 6 and 3 respectively, and flip their spots in the spellbook, while also decreasing the cost of The 3 Hunters to 6 points to make sure the spellbook is balanced. Also, if the team thinks it would be better, perhaps the Royal Breeding power should be put on the right side of the spellbook and The 3 Hunters on left, so that people don't always go left for Ents. Now, the Royal Breeding power in this situation would be made much stronger, granting 50% health, armor, and 50% less trample revenge damage from pikes, and finally it would give 200% less trample deceleration. The idea here is that with this, Rohans cavalry could do some epic charges and trample for much longer periods of time, while taking less damage, to help them survive long enough to actually do some damage against the late game pike spam of Isengard, Dwarves and Gondor. Now obviously, none of these stats are final, and the team has the last word.
My second idea is that since the heroes of Rohan are likely riding Mearas Horses, they should have better natural speed, trample damage and less trample deceleration than any other mounted hero in the game, besides Gandalf. Therefore I would propose to increase their trample damage by at least 50%, and their trample deceleration should be much slower, and speed much higher. Mearas are the most incredible horses in Middle Earth, and I feel this is not accurately represented at the moment.
Finally, I had a minor idea to add on to Hamans idea of an economy upgrade, to give Rohan a new building for economy upgrades and let them unlock a couple of different upgrades, 1 for Flour Mills 1 for Stud Farms.
Hamans Ideas: His first idea was to buff Rohans economy by adding economy upgrades to the fortress after Théoden is cured, and allowing Rohan to get upgrade discounts if they buy more armories. His next idea was to increase the strength of Spear Throwers against heavy units such as Veterans and Tower Guards. Thirdly, he proposed that my idea for Royal Breeding should be made a standard upgrade at the stables or armory, unlocked after Théoden is cured, and to replace the 3 point Royal Breeding power with something else. Finally, he proposed that Rohan should get some defensive upgrades late game, such as Fire Arrows for their towers.
Django suggested that the strength of Rohirrim Archers against pikes should be increased, but that their weakness to archers should also be increased.
Elendils Cousin and Mandos both suggested to make the Galadhrim Summon permanent, except for Haldir.
Morwereth suggested to increase Eomers Strength late game, and redo his abilities to either be more Unit Supporter of Mass Slayer oriented, instead of a mix of the 2.
Draco100000 suggested adding some new late game units, either heavy infantry or cavalry, to help Rohans late game from gaining map control. He also suggested that some kind of upgraded discount should be added, but wasn't specific about it.