We seem pretty much to have 3 "eq" playing groups, Dip Corps being the remenants of EQUK plus people from CUK, CUK and SPS (the guildname for the people from EQUK that decided to carry on playing eq 1 outside of EQUK).
From what i've seen guilds are designed to be much smaller in EQ2, not sure what the limit is but it wont be hindreds, maybe something like CoH?
The other thing is you have families - you share a surname and that gives you a way to recognise other members of the family and a communiation channel for the whole family without any of the objectives around guild success.
Maybe the way to go would be something like a ClanUK family to keep everyone intouch (effectively the cuk guild in EQ2 with all the normal trialing stuff) and then two "sub" guilds (Diplomatic Corpse & SPS or whatever) as cuk guilds - one evil based, one good so everyone is covered..
It all seemed to work well enough bringing everyone under the CUK banner in SW, COH, etc - no reason the same shouldn't work for EQ2
If one / other of the guilds decides it want's to go down the whole guild prestige route to umberness it will ned a dedicated group of officers and GM. I'm hazey on the details but the stuff you do in game effects you guild standing in the city ultimately confereing bonus to guildmembers (like increased mana regen, strength etc - a bit like DAoC when you held the three realms artifact things)
I'm sure Cad, flight or someone who actually knows what they're talking about will bealong in a min to turn my ramblings into facts
Just a thought...