In our house we have a Mac Pro, which I use for mainly for my music, and a 2010 MacBook Pro 13", which my wife and I both use for general internet, word processing etc.
I have prepared for Lion by creating a new partition on my Mac Pro (there is plenty of space on the system drive which is 640GB), and cloning my system to that.
When I have downloaded Lion, I will do an upgrade installation on the new partition, and test all my application thoroughly. As and when I am happy that everything is working nicely, I will let that partition take over and get rid of the Snow Leopard one.
In the meantime, if there are any issues, I just continue with Snow Leopard until they are resolved to my satisfaction.
I'm not sure about the MacBook Pro yet. I should imagine that I will upgrade that quite quickly, as the applications we use on that are much more run-of-the-mill than some of my oddball music software, where there may well be problems. I'll still wait until I have tested Lion on the Mac Pro, though.
I am really looking forward to Logic Pro in full-screen.