Paul. It sounds like you enjoy photography a lot. I, like many people here are quite passionate about it. Well, ok... fanatical.
You have mentioned your lens twice so it seems that you may be looking for some reassurance there so I'll tell you that the 24-105L is an exceptional piece of glass. I owned one for a while but I sold because I didn't find 24mm wide enough on the 1.6 crop body but that's a personal thing. If you are happy with the constant f/4 and the focal length that's what really counts. Quality wise, you can't beat L lenses.
As for the rest, I will be as honest and helpful as I can. A salesperson will never tell the 1st time buyer the realities of DSLR photography and I think people new to DSLR deserve to hear it. I see a lot of people who get into SLR photography thinking that the camera is going to be a magical tool that will produce great shots and they often find that they produced better images with their P&S type cameras. A DSLR is a tool and one really has to learn the technical ins and outs of it to unlock the full creative potential and produce good results constantly. Second, SLR photography is something that only a gifted few can pick up a be instantly good at. For the rest of us, SLR photography is like a good wine. It has to mature a while before its really any good.
Having said all this, I think it would be easy for someone to provide you with settings that will take decent pictures in situation x most of the time and even easier for you to rely on that good old full auto mode. But this, for me, would amount to someone cheating you or you cheating yourself out of the opportunity to be a full participant in a wonderful, creative and rewarding process.
When I got into SLR photography, I took a 30 hour course at a local college which led to several more courses. It was a great experience and I strongly suggest that you do the same if possible. This type of learning is not for everyone but it allowed me to build a local network of people interested in photography. There are also a number of instructional books and videos that you can access, either through retail purchase or even a public library.
So that's how I see things, Paul. I'm sure that people here may agree or disagree with me but it's just my effort to provide what I feel is the best assistance that I can to someone who would seemingly appreciate it and benefit from it. I sincerely hope that this is your interpretation as well. Good luck.
Sometimes not taking a photograph can be as problematic as taking one. - Alex Webb