Nissan,
This is a ditto post. I think what I say has already been said but its worth saying again.
I know some things about building. I never seriously thought about being my own GC when we built our house. When we found our builder we knew we had found our builder.

The wife and I litterally looked at each other and said we found our builder. I have talked with GC for years. I can think of two that I would have let build our house. An one of the two did build the house.
Remember you need to trust the GC. You will be married to him for along time. We spent years with our builder going through design and cost cycles before finally building. The GC is going to have a huge amount of YOUR money in his hands. If you have the slightest bad feeling about a potential GC. Run away. If the little man on your shoulder is ringing a warning bell. Run away.
A friend of mine got laid off from his career job. He went to work as the sales/office guy for a GC. I helped him buy and setup computer systems for the company. I interviewed the builder and I would not have trusted him to build a dog house. Another friend of ours who was involved with buying land with us and found a good GC. He built a quality house for them. He said something to me in passing one day the ticked me off. That comment cost him a contract.
Our builder had turned into a friend. His son and one of their workers has been going after some of the nits that needed to get fixed on the house. Its taken them almost two years to get here to do this.

That sounds bad but the long delay is OUR fault. I think most GCs after a year would have told us to pound sand. I was hoping to work from home tomorrow when they would be here working in case they have problems. I'm not sure that will happen at this point so I'm sure we will just leave the door unlocked and let them get the job done.
I'm not sure its possible to find a builder like we did but if you can its worth the effort.
Eddie hit the nail on the head about some subs. I was listing all of the good subs we had. The list was too long so I'll go after the others. The framer was ok. But his crew barely spoke English. They messed some stuff up. The HVAC guy, well I won't get started on him. What he did works but he gave no thought about the impact of his work on other subs and on the house design. Our trim sub was an ex convict heroin addict. Real nice guy. His crew did great job. I think he has a handle on his problem but you never know. The dry wall guys where on Meth. They worked like maniacs. I work hard and fast but there is no way I could keep up with the pace these guys kept much less lifting the dryway. They sent me to town to buy drywall screws they said they needed. They paid for the screws. They never used them. Just wanted me out of there even though I was working outside the house. They wanted to be alone to smoke.
How do you get good subs? You have to know them and use them. I think it would be very hard to do this if you are not doing this as a full time job. If I'm a GC and I use Joe. You want to use Joe. Joe can work with me or Joe can work with you but not both. I'm going to get Joe since I have been giving Joe jobs for years and will continue to do so. You only have one job for Joe.
The Pro GC is very likely to get discounts on materials. You might be able to as well. We worked out a 10% off deal with HD. But that takes time to do. I spent many an eight hour period at HD picking stuff out and picking up. My wife did the same and we both spent a fair amount of time onsite. I had a full time job. She did not. We also had to fix/clean up our old house to get ready to sell which was very time consuming. I don't think we could have been the GC just because of time issues.
I'm sure there is more but its late and I'm tired.
Later,
Dan