I use a number of scanners, for 35mm film, a Polaroid SprintScan 4000, worth every bit of the $100 it cost me. Film grain becomes the limiting factor in scanning.
For larger negatives that are under 4x5, as well as 35mm slides, I use my Kodak SLR/n on a Beseler Dual Mode Slide Duplicator. Quick, easy post, as I have a few actions set up in Photoshop to handle neg/pos conversion and basic level issues. Great for prints up to around 10x15 or so.
For 4x5 and up, I use either a Umax Powerlook III or a Linotype Opal Ultra, depending on what the final resolution requirements are.
Software in all scanner cases in Vuesoft, though I have Silverfast and LinoColor for the Lino, the Vuescan software has a much more streamlined workflow.
An example of a 35mm negative, scanned at 4000 ppi, below:
1_6 by
epatsellis, on Flickr