OH and Geoff, re-reading the thread and re the distributions, I think it really comes down to you deciding which you like the look and feel of best.

On OpenSuse, unless disk space is an issue, I would suggest having both KDE and Gnome desktops available on the install and playing with both. XFCE is also a possibility that might be worth a look if running on an older/slower machine.

I've never tried Gnome and KDE together with a Ubuntu type installation so I don't know if they work together easily or not but if your impressions led you to believe you like the KDE desktop and want to try it on Ubuntu, there is Kubuntu. There is also Xubuntu which has XFCE.

I try to avoid using "The best Linux" as I don't believe there is one. There is just the distribution that suits you the best (for me, clearly OpenSuse/KDE and I find Yast a strong "selling point" - for someone else maybe Fedora, etc.).