Which PDA?
That depends on your use. If you like to do everything you can, get the Mogul as Scott suggests. I will be upgrading my 6700 to the 6800 Verizon model when it is out and my contract allows. If you are like my wife who needs push e-mail or a facsimile of push, the Treo works great but it doesn't like lots of applications as it tends to lock up due to lack of ram. She can run GPS, get e-mail notices every five minutes, respond to them and have her business calendar access as well.
If you have to worry about cost on these PDA's you probably don't need one and it would be more hobby for you. For me, the PDA is a perfect extension of my laptop when away from the desk, hotel room and places where I used to have to lug along a laptop for my work.
Pocket dish is highly restrictive since you have to load what you want to watch. and, it only does one thing, play stuff you recorded from your DVR. With sling and the PDA with broadband, you can watch any live TV PLUS any thing you have recorded on the DVR. With a Broadband PDA you can look at Youtube stuff too. You have to have a cell phone, don't need an extra device. Sometimes while I am in a hurry up and wait as in a long line, I make use of the time and pull out the PDA and play a game, work on some work stuff with Remote desktop, watch a TV show, listen to a podcast, surf the web, catch up on sat guys forums, etc. All using one device I would have with me anyway, not a suitcase full of different devices that do single things each. I carry about 12 Gb of stuff with me on SD cards, an SD to USB card reader, a pair of reading glasses and a spare battery plus a BT hands free earpiece. All on a small belt holster I custom made.