I highly recommed these, I have several including one with all the bells and whistles, but I tend to only use the Zoom All on my Space Navigator - so that is what I would recommend.
When I got my first one (free demo) (Space Pilot) I was nearly ready to put it back in it's box and put it on eBay.
Then I decided to give it one more chance.
I went into the 3D Connexion Control Panel and change the behavior of the Zoom/Pan (so that pan up/down matches behavior of pan left/right) and I was flying like a pro in minutes.
Now I am always reaching for it when I don't have it (in travel).
I also use with Google Earth to "fly" down my routes when traveling to a city that I am not familiar with.
When I arrive, I already know all my turnpoint landmarks.
I would love to have one of the new wireless devices.
I have one of the simple ones, the SpaceNavigator. I mostly use it just for SW, but I wouldn't want to do without it. The only drawback, and it's easily overcome, is I had to train myself to keep my hand off of it when working with a 2d sketch.
It really speeds up rotating the model when mating, and is especially helpful if you work with large models. Last week I was without it for a while working with a 600' long model. Just about wore out the scroll wheel on my mouse. Also good for zooming in working with drawings, much faster than using the scroll wheel.
I also like it because there are certain operations when you can't control your model with a regular mouse, such as when editing a design table, but you can still manipulate it with the 3d mouse.
I started with the Space Taveler (8 years ago). It is not supported any longer. I now have a Navigator at home and a Space Mouse Pro at work. It will take 1 to-2 weeks to get used to using it and then you will be lost without it. Even though there are UI improvements every year to SWorks, there is still more than enough value in using it to justify the cost.
FYI - the first Wireless Navigator just hit the market. The Navigators only have 2 configurable buttons along with the 3D-Control pad but the updated drivers will soon allow each button to have 4 sub-functions (kind of like Mouse gestures)..
I haven't looked too much into 3D Mice, but i found a video that might help you out:
There are thousands more videos on Youtube that you can look up. Also what you can do is find a couple of the big name 3D mice, and look at the reviews of them. Hopefully this helps you out in your search.