Phil,
I started a thread asking some of the same questions this Spring and got some really good suggestions. Since then I have purchased and have been very pleased with a Epson Perfection V500 with Digital ICE. I have scanned somewhere in the neighborhood of 500 color and b/w slides, that many or more of negatives as well. I was flabbergasted on how simple it has been for me. I had some slides that I thought were toast, Success! I have some photo's from the early 1900's and a tad later. I am not working on flat photos and documents.
At the same time I purchased a Minolta Dimage Scan Dual IV like new from a family. They had bought it to do some slide work, but as it turns out, they were the wrong format. Anyhow, I never did use it, it is currently in the box gathering dust. The Epson worked quite well for me.
FWIW- Do it, and do it NOW!! If you are securing family heirloom photo's you will find there are family you may not identify and will need others help. My Grandmother was developing Dementia and she had volumes of history, so I rushed at the first of the year to get them from her home. After I got them I proceeded to scan a fast as I had time for. Well long story short, she rapidly worsened and is now in a home. And to top it off all of my fathers Vietnam photos were in with the stuff also, he passed in March before I could have him tell me about them. Now I have literally a thousand scans and lots of questions.
Let me know where you go with your choice, if you should decide to do a slide specific scanner, I would be happy to send the Minolta mentioned earlier. Not sure what it would take to get it fired up, but I hear they are great as well. But they are only for slides. Just a thought.