Okay, this is actually a double barreled question, sorry!

1) My primary *A airline is United and I've got their airline card. Does it make sense for me to carry a fee/no fee airline card from a *A partner as backup in case they can provide a better fare than United? For this secondary *A airline I'm thinking of US Airways.

The airline credit card(s) will be my primary day-to-day card for purchases like gas, dining and monthly recurring fees (wireless, cable and Internet access at home).

2) I've got Hilton as my primary hotel for when I travel and Hyatt as a backup, but with no cards for either. Is it worth bothering getting cards from the hotels if they will only be used when I'm staying at the properties mentioned?

Thanks!

Eric