you should not divide your earnings between multiple programs.
You should choose one alliance, ...
If you will be using Star Alliance there are three domestic members: ...
You should also look at the Alaska Airlines program. ...
*A - Star
With your spend of 1-1.5k / month, if you can put most of your spend on the Amex, then all you need is a free visa or MC.
Even if US does not fly to many places, the status miles are given for all alliance flights (but not the double or triple bonuses).
Wide coverage for award travel with *A to almost anywhere.
The US chart is good still for use.
US also has insane promotions to fill up your accounts
US gives free upgrades to elites, but you may not get that as a silver.
Free luggage allowance and priority boarding
Alaska
Is nice, and has advantage of accruing miles on several non star US airlines.
Award cancel fees are low 50$ vs 150-250 on US.
Good customer service