Thanks but how do you do two things:
Create a guest network on fios but still have it set up to use a password.
You don't create a guest network as such unless your particular version of the FIOS (there are lots of models I think) can also do guest network.. I do not have a FIOS modem so I cannot tell you.. but you simply use the existing passworded wireless for guest.
Use the TC with a different network name.. thus you have a guest network with password.
The 3rd suggestion
3. Roaming network where you have the same name, same security and password.. and the computer will choose whichever network is the best in the location. This is fine.
Roaming network is exactly what I have described..
Same SSID.. same security same password.
So if the FIOS router has FIOS as SSID. Set wireless name in the TC to FIOS
If the FIOS has security to WPA2 AES so does the TC.. WPA2 Personal it is called.
If you set the FIOS wireless security password to qpasogfjgjh set the TC wireless security password to qpasogfjgjh
You now have a roaming network.
See
http://support.apple.com/kb/ht4260
The apple instructions are for two apple routers but it makes no difference if they are two FIOS routers or a FIOS and an Apple router.