I think I've settled on the Handspring Treo 600 as my phone of choice. It has a tremendous amount of goodies in it, and with an SD slot, I can punch in a half a gig of storage space for MP3's. Bonus!
Now for the next step. The Treo 600 apparently works with AT&T Wireless, Cingular, Sprint, and T-Mobile. My current phone is workin with AT&T Wireless, which as far as I can tell has the -worst- phone support on the planet, but the service and coverage has been outstanding.
My requirements are unlimited data access (even as a 'wireless modem'), and decent phone coverage in the Metro Boston area.
Here's an outline of the services offered. Unfortunately it looks like AT&T doesn't offer an unlimited plan at all, so that leaves Cingular or Sprint for this area (no T-Mobile?)
I'm leery of Sprint because they have a 'custom' network - their PCS stuff. That'll lock that phone to the Sprint network only, right? But Cat has a GSM Cingular cell phone, and the coverage is cheezy as all git out. She has a terrible time holding a signal.
I'm leaning toward Sprint. Thoughts / commentary?
I'm happy with my Sprint service and coverage.
see treocentral.com; particularly the discussion boards.
ATT has unlimited GSM GPRS for $40..$50. ATT & Cingular are soon to be one company and you can already roam on Cingular from ATT. You may need to convienently neglect to tell them it's a Treo since they both prefer not to sell unlimited to PDA devices.
Also: http://del.icio.us/bhyde/treo