I have been working on optimizing scanning of 4x5 black and white on a Canon 9950. I do not do color and am not addressing color issues.
Conventional wisdom, reflected in recent View Camera articles, is that you should do a lot of processing in the scanner software, and that many people think Silverfast, with its many bells and whistles, is a good scanning choice.
My prejudice is for scanning once to generate a master file with as much info as possible. I quit using Silverfast and moved to Vuescan - which gives the most control over the scanner and the output file. I oversample - I scan at 4800, even thought this does not really improve resolution much over 2400, because it gives me 4 data points to average to reduce noise. I output the raw file - the linear output from the CCD. I set Vuescan to generate the data from the green channel because that is the sharpest one on my scanner. You can change this based on your scanner's characteristics.
Unless your scanner supports different exposure values, the raw file contains all of the possible info the scanner can put out. I downsample the raw file in Photoshop or PWP, using bicubic sharpening. I shoot for about a 4 fold reduction in file size, from about 770 megs for 16 bit B&W to 180 megs. This averages out a lot of the noise and gives a sharper and smoother image than does a 2400 dpi scan that is used at native resolution. Once I have resampled, I rotate the file and flip it to get the orientation right - I scan emulsion side down, so I get a mirror image. I then invert the image and save this as my master file.
You use levels to set the white and black points and use the gamma slider to set the midtones. You can do this as a layer if you want to tinker with it later. At this point you can see the detail so it is the time to do spotting. You then use curves to fine tune the contrast.
Vuescan has a free trial - give it a run. I think this gives a very good result and makes the best of the technology in the better consumer scanners. I am sure a drum scanner does a better job, but the costs are high, unless you want to take the time and trouble to run your own. I will be doing a comparison at some point to determine what print size it takes to really see the difference. With properly exposed negatives I do not think the better handling of dmax with a drum scan will matter much, nor should the blooming you see with chromes be as much of a issue with negatives.