A very timely thread, and some great advice!
I was in the market for a new phone (the ancient i-MATE JAM was slowly degenerating into old age, getting to the stage of needing a reboot once a day to fix its scrambled memory cells), and was leaning to the iPhone.
After reading through this thread, however, I took a closer look at the HTC Desire. All the reviews seemed to rate it above the iPhone. After looking at each side by side, the standout for me was the screen, the iPhone's looked a bit fuzzy and dull by comparison. apart from that, it did everything I needed, plus seemed to be more customisable.
So I ended up getting the HTC, and so far am very pleased with it. I've downloaded the GPS tracking app, so I'll be able to see how accurate my circuits are!
So again thanks to the contributors on this thread for steering me in the right direction!