Always. I always adjust my white balance if it needs it.
I do 3 minor tweaks to all my images.
1- White balance
2- Punch up the shadows as smidgen
3- Adjust exposure a smidgen to get it just perfect (about 1/4 of a stop more or less).
The shots you might have seen in the books might have been HDR shots. You braket 3 (or more) shots and then merge them in post to get a good dynamic range.
It looks more natural when done well because the human eye is much better a capturing a wide dynamic range than a camera sensor but it can look like garbage if done incorrectly.
Good example of HDR:
http://digital-photography-school.com/19-beautiful-examples-of-hdr-done-right
Bad example of HDR:
http://www.google.ca/imgres?um=1&hl=en&safe=off&sa=N&biw=1680&bih=949&tbm=isch&prmd=imvns&tbnid=9uvl3ygDRE1-eM:&imgrefurl=http://barrysphotoblog.blogspot.com/2008/09/another-wimberley-hdr-good-vs-bad-hdr.html&docid=7NdBs-gEt__znM&imgurl=http://www.pbase.com/blarmer/image/103176246/original.jpg&w=800&h=532&ei=REOIT4zgKqTb0QGui7GzCQ&zoom=1&iact=hc&vpx=295&vpy=168&dur=439&hovh=144&hovw=192&tx=97&ty=106&sig=114182614698033747138&page=1&tbnh=144&tbnw=192&start=0&ndsp=37&ved=1t:429,r:1,s:0,i:68
http://www.google.ca/imgres?um=1&hl=en&safe=off&sa=N&biw=1680&bih=949&tbm=isch&prmd=imvns&tbnid=URPzBUyxictmbM:&imgrefurl=http://www.flickriver.com/photos/kushaldas/2433830425/&docid=C_BwByfEE2dOVM&imgurl=http://farm4.static.flickr.com/3022/2433830425_d8f6682a97.jpg&w=500&h=335&ei=REOIT4zgKqTb0QGui7GzCQ&zoom=1&iact=hc&vpx=499&vpy=167&dur=302&hovh=145&hovw=194&tx=109&ty=106&sig=114182614698033747138&page=1&tbnh=144&tbnw=192&start=0&ndsp=37&ved=1t:429,r:2,s:0,i:70
http://www.google.ca/imgres?um=1&hl=en&safe=off&sa=N&biw=1680&bih=949&tbm=isch&prmd=imvns&tbnid=0LyvnmYBuBmgOM:&imgrefurl=http://anarchyjim.digitalanarchy.com/adobe-photoshop-plugins/i-hate-hdr/&docid=PgVegYnqO3_TEM&imgurl=http://anarchyjim.digitalanarchy.com/wp-content/uploads/hdr_hate.jpg&w=550&h=366&ei=REOIT4zgKqTb0QGui7GzCQ&zoom=1&iact=rc&dur=328&sig=114182614698033747138&page=1&tbnh=144&tbnw=192&start=0&ndsp=37&ved=1t:429,r:4,s:0,i:74&tx=111&ty=79