Dennis,
E-6(Ektachrome) films have come a long, long way even in the past 20 years.
Today's ISO 100 E-6 films-like Kodak E100G or Fuji Astia 100F-have a much tighter grain structure than even the ISO25 Kodachrome(which hasn't been made in about 10 years). This is thanks mostly to modern technology in grain structure, which allows higher sensitivity in a smaller grain. Kodak's E100G, in particular, has what is probably the tightest grain of any film currently on the market.
As for color-Kodachrome colors do have a certain look about them. It's a high contrast film(which makes it difficult to shoot well). The contrast tends to give it a certain "pop" but the colors themselves are not overly saturated and tend to block up pretty badly.
Fuji Astia is something of a benchmark for being color faithful, and Kodak E100G is not far behind. In the Fuji line-up, Provia give nice, saturated colors and Velvia gives over-the-top "Disney" colors. Incidentally, Velvia is my favorite for landscapes.
As far as archival-the old E3 and E4 process films were pretty much universally bad and were lucky to last 20 years. Modern E6 process films are great, and are at least the equal of Kodachrome. The rated life of Velvia is given as greater than 80 years.
Whatever the case, though, Kodachrome has a look that's hard to replicate, and I hate to see it go for no other reason than it means less film available(yes, I still shoot a lot of film).
Terry,
I have a Canon flat-bed scanner that's about 4 years old which I use to scan both negatives and slides. Mine has a top light to allow reverse illumination of the film. It can handle 4 35mm slides, or two 6-frame strips of 35mm film. It can also handle a strip of medium format-equal in length to 4 frames of 645, 3 frames of 6x6, or two frames of 6x7.
At the time I bought mine, I wish that I'd bought an Epson, as they were considered the best for flatbeds. The current models are the V500 and V700, both of which are several years old now(I don't think scanners have advanced much) but are still well regarded. The V700 has a full width top light which allows 32 frames of 35mm, 8 slides, or 2 strips of medium format at a time. The V500 is smaller and has the same scanning area as my Canon above.
If you're just handling 35mm, a dedicated film scanner is a good option. Nikon is thought to make the best of these, although they're pricey. Most of these can handle 4 slides or a 6 frame strip of 35mm at a time.
Whatever you get, make sure it has Digital ICE, or the equivalent. This is an infrared system which takes care of dust on your slides. It doesn't work well with Kodachrome or black and white film, but works great with color prints or Ektachrome. It can't work miracles, though, so it's still a good idea to clean your slides before scanning-I like to use one of the anti-static dust brushes that contain Polonium-210. These are available from camera shops.
I've seen a lot of single-frame film or slide scanners for sale at department stores and places like that for around $50-100-most of these are pretty bad(from what I've seen) and I would personally suggest that you avoid them.(I see Dennis snuck in and mentioned this while I was typing).
One of these days, I'm going to experiment with using my old Canon FD mount slide copying apparatus(that fits on the front of the macro bellows) with a dSLR. I think that has the potential of getting decent quality and being a lot quicker than using the scanner.