Not sure if this will help, but assuming you have the funds available, you might pay your bill before it arrives. Using a bill-pay out of your bank account, payment is usually posted in 1-2 days. If your statement date is the 25th, log in on the 20th and find out how much you owe and pay it. Or even pay it more often than that.
Amex Plat has some great benefits, but it's not great for earning points. If you do have the potential for a lot of travel, you should consider:
1) Lounge access
2) Foreign transaction fee waived
3) Annual fee
4) Type of points earned (airline-specific or transferrable, and if so, transfer partners)
5) Elite Qualifying mile bonuses
6) Bonus categories and annual bonus thresholds
7) Tie-in with any airline you want to be tied in with.