THANK YOU for all of the comments--as a soon-to-be switcher (come on, MBP refresh!) it occurs to me that Apple should market its users as a competitive advantage.
It looks like for my fairly non-tech literate self (ruling out NAS), my options are:
1. TC: set it and forget it + router capability, but buy AppleCare due to 18-mo. fail frequency
2. Airport Extreme + external harddrive: less expensive router + backup solution, works with Time Machine but (I think) you have to manually direct it to back up
3. USB external harddrive: least expensive but you have to manually direct it to back up, and (of course) no router capability
This has been very helpful. Thank you again!