With the inclusion of Google Local Search in the newest version of Garmin XT, it is now, by far the most powerful GPS intergrated search function available.
Using garmins maping software and your computer, it is possible to remove not commonly used states from your GPS card. My garmin maps take up less the 100mb.
You can also create custom routes, and points of intrest using google maps and a service like
www.takitwithme.com
https://buy.garmin.com/shop/shop.do?pID=11413#
In my opinion, the only feature garmin is currently lacking is "text to speech". It says "turn right" but doesn't say "turn right on sycamore street." Hopefully they will update with that functionality soon.