When I want a really good but pretty easy read, I go for Michael Crichton. He wrote the Jurassic Park books as well as Congo and Sphere, just to name a few you may be familiar with. I've read all of his books, and my personal favorites are Andromeda Strain, Sphere, and Timeline. Disclosure is a little bit of a lesser know one that was made into a movie starring Michael Douglas (one of my favorite actors). Good movie, and I enjoyed the book as well. Really you can't go wrong with him. Very good books, well written, but extremely easy reading. Which is good if you have a busy schedule and have to read on and off.
Right now I'm reading Hitchhiker's Guide to the Galaxy. It's sort of a sci-fi comedy/satire and, in my opinion, pretty hilarious.
If you want something a little more classic, some good ones are Treasure Island, The Island of Dr. Moreau, Frankenstein, A Separate Peace, The Hound of the Baskervilles...
Aaaand I've given more than my fair share of opinions :)
Hope that helped.