Hi ckret01!
We have added onto two different homes. Yes, it is an extremely stressful time but I feel it is well worth it in the end. On the first home we remodeled a bathroom and added a bathroom. It was tricky because we had to finish one before we could start the other since there was only one bathroom in the house. For this job we interviewed several people we found in the phone book, checked references and then picked one. The guy was OK, did what he was supposed to and we were happy with the results. This job was somewhere between 20-30k and took about 2 months to complete.
The second home addition we just completed. We have put an over 600sf addition onto the house for my parents. It contains a bedroom, living room, bathroom, walk in closet and deck. This time we went with a guy who did two additions onto my sisters' house and seems everyone in town uses him. He'd be here a few days, do a ton of work, and then we wouldn't see him for a week. We knew this going into the whole thing. And of course, near the end of the job it seemed his visits got further and further apart.... he needed to be hounded every day. But when all is said and done it is fabulous! I love it, my parents love showing it off, and as I said before, definitely worth it. This job was between 60-70k and took about 6 months to complete.
My advice is, when you are ready, ask friends, neighbors, relatives for references, check out the contractors references, and be prepared to spend 10-20% MORE in money and time than quoted. Most importantly if you don't feel comfortable with the person, even if their work is great, he may not be the guy for you. You need to be able to communicate with him effectively and be comfortable with him in your home. These people sometimes become part of your lives, especially when they are around for 3-10 months.
Good luck with whatever you choose to do!