I'm not a GM, but have been incharge of recruitment for one guild for almost 6 years now. Personally I think its a problem with WoW. As much as I love the game, I've seen it destory many guilds that were around for 10 years prior to WoW. You need gear to do anything well and people get frustrated when they cant get it with their current guild, so they move over trying to find it somewhere else (and usually fail). We are dealing with a whole new mindset of gamers now days than 10 years ago
Two of the guilds I play with have been around since 1992 with a game called NWN and are still going. They are still around because people have to do quests from officers (ie: lead a raid on an enemy main city and hold a section for 20 min, kill X amount of L60+ players, etc) in order to become "full" members and usually a 3 month trial period. Many people freak out at that idea and leave right away. But thats the point and you end up saving yourself hassles later on. People who are prepared to stay through the trial period and complete the quests usually feel "special" and that are actually a part of the guild and not just another player.
Of course you need to have something that will make them want to stay and Diesel is right here. Getting L70 should be your first priority, From L66, it shouldn't take more than a week. Remember when BC came out the first L70's made it from L60 in 5 days. Now days it is much easier