I have been a Nikon shooter for years -- film SLRs. Coolpixes and now DSLRs. Probably because of this, the first time I picked up a Nikon DSLR it just felt "right" to me and I didn't even consider looking at or handling other brands. Later on, I did have the opportunity to handle other brands and my opinion has not changed. I am now shooting with the D200, which definitely requires much less delving into the menu than the D70 does... I don't know about Canons, what the situation is there. Most of the critical functions are quickly accessible on the D200 by either buttons or command wheels, and it is great when you're in a situation where things are changing quickly. For this reason I definitely prefer the D200 to the D70/D70s.
Aside from how the Nikon or Canon feels in my hands, there is the issue of lenses. This is critical when just starting out because one is actually not buying a camera body and lens, one is buying into an entire system. It is important to think about the type of shooting one does currently and the type of shooting one might want to get into doing later on, and whether or not there is also room for experimentation and fun. My first purchase of a DSLR was the Nikon D70, which came with the kit lens. The day I walked into the store, ready to buy, I also announced that I wanted the 70-200mm VR. At that point in time I knew that this would be one lens which would give me a lot of flexibility and reach. Now, some time later, I've added many lenses to my bag but that 70-200mm VR is still one of my favorites, stlll a shining star....Adding a teleconverter to it extends my reach further.
Today I was at the camera store and I actually did something rather interesting, I bought lenses at both ends of the spectrum, a 300mm f/4 and a 14mm f/2.8.... Why? Well, because I went in there with the intention of buying the 300mm f/4 and then after we'd pretty much finished playing with that, we were talking a bit and then Chip said, "oh, have a look at this for future consideration some time down the road...." as he slipped the 14mm lens on to the store's demo D200 and handed it to me..... LOL!!! He really didn't intend for me to waltz out of there with that lens, too, but, hey....instant love, what could I do? Just like with Bertha, I found myself looking through the lens and loving what I was seeing and then, just as with
Bertha, I was again standing there stroking the lens as we chatted.
(I've already warned him, for heaven's sake, whatever you do, DON'T show me the D2Xs!!!)
Anyway, the point here is that as one grows into this obsession -- erm, hobby or profession -- more than likely there will be a need or desire for lenses to fulfill specific photographic needs. It's important to be sure that the camera system into which one buys does offer a wide variety of lenses that will fit the camera owner's needs. I bought that 300mm for shooting at a greater tele distance than I can reach with the 70-200mm (without teleconverter) and bought that 14mm wide-angle for getting interior and exterior shots that don't have distortion and which show a lot of territory. I have enjoyed exploring wide-angle with my 10.5mm fisheye and other lenses, but this one adds its own special characteristics. I'm not in real estate, but certainly this is a lens which would serve nicely in that situation, so maybe I'll offer my services to a couple of realtors that I know....
Definitely in choosing lenses it sounds as though you've got the basic ranges nailed down: a fast 50, a wide angle and the 70-200..... certainly both Canon and Nikon have excellent lenses to offer. I think you are just going to have to spend some more time in the camera shop handling each body and putting various lenses on it, seeing how everything feels and works for you.... In the end it is your money and it is you who will be using the camera and lenses, so regardless of what works for anyone else here on MacRumors or anywhere else, the bottom line is what works for YOU.