My best advice would be less is more, so pick out your best work and include only that rather than trying to get as much as you can in there and adding mediocre work that doesn't actually show how well you can do things.

Also play to your strenghts, we had this discussion here the other day because we were going through a lot of lightwave reels and it's nice to show off skills in as many fields as possible but if you include a badly textured model that's been animated well this will take down the overall impression and you'd be better of just keeping the default material and show off the animation instead.

When you make turntables make sure that they don't spin super fast but move around slowly and show the model well because there's nothing more annoying than a three second long turntable where you can barely see anything. Also zoom in fairly close and show the wires so other people will understand what they're looking at.

Dave mentioned something the other day as well when he was working on his fluid simulation in realflow that it's nice to see complete breakdowns of a scene, he made one I'm not sure if he posted it on the site yet but basically it went from the end result to showing the settings for the wine pour in realflow, the actual geometry present in the scene including the direct light sources and just seeing this you could tell that the background was an image and that a fair few things were also done in post. A breakdown like this would show a potential employer that you know a bit about fluid simulations, shading/lighting, when to actually model geometry and also how things can be done in post. These breakdowns as well are helpful for other people who watch your reel and might want to do something similar to yours I think.

I know nothing about games specifically but it sounds like you've got the right idea. In general though I'd keep it simple and focus on getting a few things in there and spend a fair bit of time getting them to look good rather than trying to do too much.