How do I avoid problems when going from Wi-Fi to cell data connection (3G)? I have my phone (Droid X) connected to my home Wi-Fi network, but when I leave it can take applications (Google Maps, Rhapsody, etc) probably 10-15 minutes before they function normally without either doing nothing and/or giving data connection errors.

Something that may be telling (or meaningless) is that the little "3G" icon on the notification bar doesn't appear for a good long while.

Disabling the Wi-Fi on the phone after the fact doesn't seem to help, and the fastest method seems to be just power cycling the whole device.  Is there some better/cleaner/faster way?
You could try using Quick Settings to toggle the 3G connection.  It has seperate toggle switches for 3G and Wifi but when wifi is on it automatically turns off 3G.  When I click the toggle to turn on 3G it automatically disables the wifi.