I have the apple wireless keyboard, Magic Trackpad, and a cheap logitech M510 wireless mouse that I use. I have the Meshwe Bluefin that I use to connect the keyboard and track pad together for easier use on the couch and lap.
Meshwe Bluefin
I have a very small desk that my 22" LCD Proview monitor sits on (it was a freebee from a friend since I owned laptops before and didn't need a monitor) and my Mac Mini sit on so I wanted something that I could connect the keyboard/trackpad together and then just keep the mouse separate. I love the gestures on the ipad so I figured what the hell, get the trackpad for the mac. My mini sits right next to my Vizio 47" LED 1080P, 240Hz TV and I use that for my additional screen for when I am on the couch to either do work, surf the internet or watch a movie. The monitor is really there so that I can keep doing work on the mini when the TV is being used by someone else. I download a lot of video files and they need to be converted to .m4v format and then organized in iTunes for playback on my three ATV3s in my house.
The bluefin works well enough but doesn't keep the trackpad from being able to rotate in the groove that the battery housing goes into. That is good and bad. Good because that is one way you are going to get it out by rotating it up and then popping the battery part out. Bad because it gives a false sense of stability. It feels like the track pad is going to fall off/out of the bluefin piece, but so far nothing. It does work well to keep them both together and I am happy with it overall. There are a few other options out there that I looked at, some wouldn't let you use the magic trackpads click feature (the bluefin does allow you to click).
As for general mouse use, when I am at the desk and I need to do a lot of clicking and moving around I use the logitech mouse. I use the trackpad for gestures mostly.
I haven't tried the MM though but heard a lot of the same issues, hand cramps trying to use it and the majority of people said the same thing, just use a regular mouse and save the $69 (minus the difference of the new mouse unless you have one already).