Regardless of the separation of lecture and lab into different courses, it's sad that lab usually doesn't have the prominence of lecture either in credit hours or in 'importance' as alluded to by most instructors. As geodome stated, I think it's pretty common experience to have students do a lab out of sync with their lecture, thus really questioning the entire relevance of it. My experience was even worse--the lab instructor didn't communicate with the lecture instructor and the two courses had nothing to do with one another content wise.
That being said, I personally like lab more. I tend to think for most students the lab simply reinforces the lecture material, so they should be taught together. However, for chem majors whose line of work it is to do research, I think the lab definitely is more important and needs a lot more prominence. Out of all the labs that I've seen, one was fantastic. Dr. Don DeCoste (U of Illinois) does a fantastic job with labs by using an innovative approach--he gives no procedure for how to do something. He gives the students a list of reagents they can use and presents them with a problem: how to accomplish a certain reaction, how to measure something, or how to test a hypothesis. It's up to the students how to do it. They then present their procedures to Don, who gives them the go ahead or helps them to revise it and gives them more questions to think about. I really like this idea, because it makes the students really take ownership of their procedures, not just read through it and wonder what the hell they're doing. When you think about it, that's what research is: you try and figure out how to solve a problem, then you have to do literature searches and come up with your own procedure. Obviously, in the interest of time, the lecture relates closely to what's going on in lab, and the choice of reagents is pretty limited, so they can't come up with some really crazy stuff, but it is still very much a thinking process.