The Garmin Nuvi is a pretty good choice, as are the TomTom units - TomTom ONE is very nicely priced (at least here in the US). Both are very easy to use.
The Nuvi is available in European, USA and (new) European+USA editions. On the TomTom side, they have USA and European editions of everything and I know their high-end model 910 has Europe+USA, but I'm not sure whether any of the rest of the line is bicontinental (just in case that matters to you).
TomTom is a European product, Garmin an American product, but both are keenly focused on succeeding in the others' continent as well as their own. Still, you may find the TomTom has a little more of a home-field advantage in Europe, just as the Garmin does in the USA.
The TomTom units are a little more feature-rich and customizable (you can buy optional cebrity voices for them, choose your own color schemes, etc.), while Garmin seems to have more of a "just stick to basics" perspective in their consumer automotive lineup.
There are many other brands out there now as well, but those seem to be the two heaviest hitters, both with solid products and a real ease-of-use focus.
A couple blogs you ought to read are navigadget.com and yournav.com. You also might also want to look at gpspassion.com's forums, though they're much geekier. A couple other good blogs are gpslodge.com and gpstracklog.blogspot.com, though they have more of a USA orientation.