I have, an would recommend a Quantaray bag from Ritz camera. I had the same needs as you for a carry bag, and they had quite a few to choose from. I brought my Canon T-70, lenses and flash with me and I just tried a few. The one that I bought cost about $15.00 or less and is made of padded nylon, and loaded with pockets. It is designed to carry an SLR with a 70-300 zoom attached. I can place the T-70 body, a 299T Flash, a FD 100mm 2.8, 50mm 1.8 and a 28mm 2.8. Plus I carry film, a lens cleaning kit and a lot of other stuff that I probably don't need. This bag has two straps, one for your waiste, and another for your shoulder. I usually just use the shoulder strap, and the other tucks into a pouch.
I also use this same bag for my Nikon N-70. I place the N-70 with either a 70-300 zoom and add either the 28-105 zoom, or the SB-28 flash depending on what I'm doing. I can't fit both lenses and the flash, so it is one or the other. The Canon gear is smaller, so I can take more of it. But, this is a relatively small package for 35mm SLR gear.
I think the only way you will really know which bag is right, is to look at a few and see how your equipment fits. You can also check Best Buy, and other places that sell camera gear. Origionally I was looking for a slightly smaller bag, but ended up with the one that I have. No complaints, as it gets a lot of use.
Jeff