Butcher block counters that are used for food preparation are not stained, from what I have gathered. This is due to the fact that wood stains contain toxins in them that would not be suitable to have contact with food.
A few factors go into the wood selection of your butcher block:
1. The variation in natural wood colors means that many different wood types are used for butcher block counters. You can choose from extremely blonde to almost black
2. Harder woods are less likely to show cuts and scores like soft woods will, but they will also dull your knives quicker.
3. You also have the choice of which way you would like the grain to be on your counters-face grain, edge grain, and end grain. I think that edge grain and end grain are more popular due to their strength and ability to withhold excessive cutting.
As far as life expectancy, here is a link for butcher block maintenance
http://www.houzz.com/questions/22477/How-should-I-finish-butcher-block-counte---
And for any more questions that you may have, or if you are ready to purchase, John Boos has been selling butcher block since 1887
http://www.johnboos.com/