You mention comedy sci-fi. I'd strongly recommend 'Old Man's War' by John Scalzi. It was a mobileread bookclub book one month. It has two sequels that are equally entertaining.
Since you are relatively new to reading, i'd recommend you put in a few classics from time to time. War and Peace, Les Miserables etc. Some of the old literature although maybe hard to get through at first is well worth the effort. My favorite classics (Not in any particular order)
War and Peace
Catcher in the Rye
A Tale of Two Cities
Gone with the Wind
A few in the above posts are true sci-fi classics, and I'd add Farenheit 451 to those.