For phone service I've always used a pay-as-you-go. My first was a Virgin Mobile phone which I never really cared for, and now I have a tracfone that I actually rather enjoy. I still don't use it much, but the battery life is incredible compared to my old one and the display is much nicer. I can also get more bars in more locations.
As for a PDA, I've had 4 different PocketPCs ranging from PocketPC 2002 to WM6, and a Palm Tungsten|E. Sadly, I've never done much with any of them except some programming and playing games. My life would probably be a whole lot more organized if I started using the DA part of my PDAs