As you move up the scale....
Most people use the Nikon Coolscan V (~$600) or 5000 (!$1200) (or out of production Konica Minolta Dual-Scan IV ~$300) film scanners for their 35mm work. The 5000 is obviously the best but the $300 Minolta is quite good, a bargain.
And an Epson 4990 (~$300 old model) or the current 700 or 750 (~$500+) model flatbeds for scanning large format film and plates. The 700-series is better built but the 4990 will produce just as good a scan.
The best consumer scanner for medium format is the $2200 Nikon Coolscan 9000 but people will use the Epsons if that is all they can afford.
You can also get an Imacon (Hasselblad) that will do 35mm to 5x7 film (not glass) starting at a few grand for used, they've been made for over a decade in several versions. They are generally better than the Epsons and Nikons.
And then there are the older high-end flatbeds made by Kodak/Creo/Scitex or Screen or Fuji, etc. and of course older high-end drum scanners made by many manufacturers. They are the best but the investment reflects that. Most people send out to services for high-end scans, $60-$100 per scan is not unusual.
They all operate on the same principals so I'd start with the Epson flatbed myself, and then invest more time and money as you gain experience. Lenny is right that people are silly about spending thousands on camera gear only to scan on a cheap scanner is pretty dumb, but don't dismiss the fact that you can do fine work with the basic gear.
Frankly if I were confronted with thousands of family slides (which I am actually... I am just too lazy to even address the issue) I'd definitely consider using a place like ScanCafe (which has a good reputation). The Nikon and Minolta scanners do fine but they are slow to use, and even if you're retired it can be really tedious. It might also help you avoid having to buy a film scanner.
As for the operating software for the Epson/Nikon/Minoltas (and some others) the choices are VueScan, SilverFast, or the bundled Manufacturer's software. They all have their pluses and minuses. I like the Epson software fine and used VueScan for the film scanners myself. None are perfect solutions.
Bookmarks