If you want the more mature player then a late night raiding guild maybe the answer, people who work and have families struggle for time to play and raid so when then do get the chance they very rarely let the other members down.
Most "late night" guilds are pretty good. The problem that we faced with our guild was the first 6 months were great. It was friendly, everybody in for the same reasons. Then the burnout stage started, late night starts and finishes, kids and jobs and people started to tire. We then had to recruit to fill the gaps that started appearing so people could continue to raid, but in may cases those holes were filled with people that were not necessarily only able to raid late.
Shame, I loved my old guild, but slowly after time the rep that we built as a solid friendly and effective raiding team (that raided later in the evenings) was our downfall as we attracted people that wanted the solid and effective raiding but were not so much bothered by the friendly and late night aspect.
Class and role specfic encounters are always guild killers. Dual specs have eased this problem slightly with role, but how many times did we have to cancel raids or really really struggle due to not having a druid tank or a DK* not signing up.
* A DK with half a clue on how to play their class, I know not having a DK sign for a raid is a rare event, but we needed ones with the basic knowledge of not gripping Malygos.. or even not gripping anything at all for example.