Just because I want to make your life more difficult (no, not really), I might throw one more spanner into the works. Personally, the trick of multiplying focal lengths doesn't work at all for me. In small format, I like wide (and even exteme wide) angle lenses. In medium format I prefer normal to slightly long lenses. With each increase in format I find that I like longer lenses, so by the time I get to 8x10, my favorite length is 480mm.

Luckily, if you buy a large format lens and find that you don't like it, you can usually sell it for close what you paid for it. So it's worth experimenting a bit, if you don't mind the effort of selling stuff.

Having said this, I strongly recommend that you buy one, or at most two, lenses and just use them for a while. Avoid collecting many lenses at first...that way lies madness. (I speak from experience...)

Best of luck.