I would call up Hilton and ask them how many lifetime nights you have. If within striking range of 1,000 Hilton Honors nights (one of the Lifetime Diamond requirements), I would focus on that.
If you will be short of the 10 years Hilton Diamond status, that can easily be obtained through the Hilton Aspire AmEx.
Then switch to Hyatt or Marriott if you are still traveling.