I've carried an AT&T Tilt for nearly a year now as my primary personal phone. I truly love this phone, Windows Mobile 6, GPS, WiFi, full keyboard, 3 mega-pixel camera, and high speed networking is fabulous. I've been with AT&T for several years now. I was an AT&T Wireless customer, then I was a Cingular customer, now I'm an AT&T customer again so I've got a really good deal on a tethering plan for this unit as well which makes it Option 3 in my always connected plan.
I've just begun to carry a T-Mobile Dash as my work phone. It is replacing the 8700g (below) which I've carried for the last 2 years. While it doesn't have all the bells and whistles of the Tilt, it is running Windows Mobile, and so I can keep my mobile helpers on it as well.
My Blackberry that I've carried for many years is great for all the reasons that BBerries are great, and horrible for several other reasons. First and foremost, the thing refuses to power of nearly any scheme other than a true Blackberry charger. In my opinion, if I can't charge you off of a USB connection without special software installed, I'm not interested and that was the deal breaker for this otherwise great phone.
Sprint Wireless Card
I carry a Sprint Wireless Card as my primary mobile connectivity option (Option 2) in my backpack. I have nothing but gushing things to say about Sprint's network. As you can see from above, I commonly have had a chance to work with every network except Verizon for data, and Sprint is far and away the king. This wonderful ExpressCard slot item just works, and that is what I want from my technology.
So about now someone has to be asking ... seriously? You carry a router? Heck yes! My Linksys Compact Wireless Router has solved a ton of problems for me in the past, and takes up so little space I often forget I've got it until I get desperate. When I land at a hotel room for a conference, I'll pay for internet for my room and then share it out via this little baby. It has also saved the day when visiting clients without wireless capability (NOTE : Ask about this folks, often they don't have it for good reason) or when I'm on personal trips to family. It has also saved the day at the first We Are Microsoft event when we overloaded the wireless capabilities of the sites router. I plugged in and took Team Sogeti and several other teams onto this unit to clear up some spots. Get one, you won't regret it.
Eons ago, when .NET was young and I was trying to learn it, I attended a ton of MSDN events. Inevitably you got a little bag of swag, and in one of those bags I got this little gem, a self-winding network cable. It lives in my backpack, comes out when the client doesn't have wireless and has saved the day many times.