If you shop for the lowest price and best buy, get the 300 dpi scanner. It will deliver for you, you'll be very happy with it. For web site or casual home use, it's plenty. I've been very pleased with my E3, it's been fantastic. See two links about CIS, here and there If you generally buy the better models of things, then get the better scanner and don't look back.
Prices are really low today.
You will probably never scan photos over 300 dpi, but you'll have a better scanner. 30 or 36 bits will also allow a wider range of tone adjustment before internal color saturation occurs. And you get 600 dpi, useful for Line art and text documents. These are subtle features, some of us won't ever notice them, but many people, particularly the commercial users, think they are very worthwhile. Home and web site use are typically very light requirements for a scanner.