I agree with Diolla. If you have any assets at all you're underinsured. I'm also covered at 100/300 and worry a bit at that. Collision probably isn't necessary. Collision only helps if an accident is your fault and most of the time an accident won't be 100% your fault. Futhermore, you probably wouldn't bother to fix your car completely and you could probably get it running comparatively cheaply. (Of course you might truly total it -- that's the risk of not getting collision. So, is the $3000 or so you'd get in that situation worth the coverage cost? That's the question you have to answer.) Personally, I like comprehensive. Why? It's pretty cheap and dh and I have had 2 cars hailed out and 1 car flooded. It also usually covers glass (without the deductable even), which comes in handy. Now, you could argue that I'm "comprehensive prone" and you'd be right, but it's something to consider.
