Originally posted by Joe Nation I have a 28mm SMC-A, a 40mm DA Limited, a 50mm Lensbaby (and previously a 50mm SMC-A) and a K 55mm. I tend to shoot street and landscape, and I guess the 40mm has spent the least time in my bag recently (partly due to autofocus and being ludicrously small). But I find the 28mm a very useful length too. The 50 and 55 rarely see much camera time, except for portraits. Its worth mentioning that I also shoot on film, where the 28 is a fair bit wider and the 55 gets a lot more use (not too far off the field of view of a 35mm on APS-C). I find myself yearning for a wider option, maybe a 15 or thereabouts (close to a 24mm on full-frame). The only zoom I use often is the 17-28mm fisheye, which I use almost exclusively at 17mm (27mm equivalent on full-frame).
So my advice to the OP would be around a 28mm or 30mm for near-normal focal length, and around a 15mm for wide. The 50 is great for portraits and short-tele stuff.
So much depends on the person. I have a 28,35 and 50 and tend to use the 35 the most followed by the 50 and then the 28. I now have a 70 as well as the 50 is just not long enough. I too have the 17-28 but at the wide end comparing it to my wife's 10-20 it is much closer to the 15 than it is to 17mm so more like a 23 on film.
OP If you are new to primes use the 50 when you get it and you will soon see if a prime is even right for you. It is not for everyone. I started with primes with a spotmatic, went to zooms when went with autofocus (SF1n) and am back mostly with primes. My wife who went the same route is more a zoom person. Enjoy the 50 and then decide or perhaps in the meantime either a 28 or 35 will fall into your lap at a price you cannot pass by and your decision will be made for you. My 28 is a M lens and the price was right FREE.