I've downloaded Google maps to my 8900 but the application never loads up at all.
The progress bar on the screen loading the app gets stuck at baout the 1/3rd mark and remains that way for a long time.
I've deleted and re installed to no avail.
If I'm traveling in the US without a data plan on my phone can I use Google maps or will I need another app for GPS navigation?
You need a data plan for google maps. Actually except for the two below, you probably need a data plan for all of them now.
If you have a limited travel range, then you could check out Mobilegmaps (NOT google) or trekbuddy. You do need to compile and load maps for each by using 3rd party apps and/or computer.