Thanks. It actually wasn't too long ago when I pretty much had the exact same questions you've been posting. It usually took me *weeks* to find the answer or to gain enough experience to understand how to do stuff (especially topics like Photoshop or flash photography). So if I can save a fellow Disboard photographer some time and simplify an answer, I'm always happy to help.
I actually like to geotag pretty much ALL my photos. I think the only photos I don't geotag are the ones I take at home...just in case some psycho sees my photo and finds the GPS coordinates of my home.
Otherwise, I like geotagging photos from everywhere else. If I walked around a local park to take photos, I'll geotag those photos. Or, it's neat geotagging all my photos at Walt Disney World. If I'm on the monorail and I take a picture, I can see the GPS coordinates of the monorail track where the photo was taken. Or, in Animal Kingdom on Kilimanjaro Safaris, my directions are always disoriented while I'm on the ride. However, by geotagging those photos, I can see the exact spots on the safari where my photos were taken.
So you really don't have to limit your geotagging to cross-country photo trips.
With GPS receivers, you can go anywhere from cheap to super expensive. I think the cheapest I've seen is about $60 for a no-frills GPS data logger. For these types of devices, there's usually no screen, you can't see the actual GPS coordinates on the device, and the entire device is made up of like 1 button and 3 lights. However, it records your GPS location throughout the day, and all you do is download the data (GPS tracklog) onto your computer. Even though it's a no-frills GPS device, it seems to get pretty good reviews (
link).
I ended up buying a Garmin Colorado 400t (
link), which I see has now dropped a whole bunch in price!
I like having a screen that shows my current GPS coordinates. I like seeing my current location on an electronic map. I like seeing details of how accurate my GPS lock currently is. I like seeing the number of satellites my GPS receiver is locked onto, and where those satellites are in the sky. I can also use my GPS receiver to mark my parking spot at the Ticketing & Transportation Center, so I can find my way back to the car at the end of the day.
My GPS receiver also shows my current date and time. This is SUPER important because GPS satellites orbiting above us have highly accurate atomic clocks. Once my receiver is locked onto several GPS satellites, then the clock in my GPS receiver is
just as accurate as those atomic clocks! (isn't that amazing how technology works?) That's why I *always* sync my cameras' clocks to my GPS receiver's clock.
Actually, if you have an iPhone or BlackBerry, you may already have a GPS receiving inside your phone! All you have to do is find an app that records your GPS tracklog. On my BlackBerry, the downside is that using GPS seems to drain the battery a lot faster.
No matter how much $$$ you decide to spend on a GPS receiver, ultimately the key functionality you'll need is something that records your GPS tracklog. Everything else is just bells & whistles.
Hope that helps!