If you're looking for a large Android tablet, the Viewsonic G Tablet is worth considering. In size and performance, the Viewsonic G matches the WiFi iPad point for point, and costs $100 less.
Model: Viewsonic G Tablet
Processor: 1GHz NVIDIA Tegra 2 Dual-core ARM Cortex-A9 CPU
RAM: 512MB
Storage: 16 GB micro SDHC card, expandable to 32 GB
Screen: 10.1 inch capacitive LCD, 1024 x 600 pixels, LED illuminated
Connectivity: 802.11 b/g/n WiFi, Bluetooth 2.1
Ports: Docking port, USB, mini-USB, headphones, DC power input
Camera: 1.3 MP
Operating System: Android 2.2
Dimensions: 10.5 x 6.8 x 0.5 inches
Weight: 1.6 lbs
Accessories: Dock with HDMI out, USB
One shortcoming: The Viewsonic G has a 3650 mAh battery. The iPad's battery is 6500 mAh. So battery life should be about half what the iPad enjoys.
The G Tablet list price is $399. Sears has sold them for about a month. Their price today is $379. A comparably equipped iPad (16 GB of flash storage and no 3G) is $499. Staples and Office Depot also carry the G Tablet.
As shipped from Viewsonic, the G Tablet lacks access to the Google Marketplace, and does not support Flash. Viewsonic is about to launch its own apps store, and will make a software upgrade available in December that turns Flash on. If you don't want to wait, some enterprising hackers have figured out how to correct these limitations.
http://www.netbooknews.com/12883/viewsonic-g-tablet-unboxed-and-reviewed/
The G Tablet has USB ports, so it should be possible to get an external GPS receiver working with navigation software. I have not seen a web page that explains how to accomplish this, however.
For more information:
http://www.viewsonic.com/gtablet/
Viewsonic has several 10 inch tablet computers in the works. One dual-boots Windows and Android, and another runs Windows 7 exclusively. Be careful when ordering!