That's a good point. Many hotels' base-level suites, one of which you need available to apply a DSU, will be sold out far ahead of the stay -- and other hotels will have suites available near departure. It completely depends on the hotel and the dates of stay. If getting the upgrades on your bar trip are the main consideration, I'd get the Diamond status now and apply the upgrades while you can (assuming they are presently available), unless you do further research and make yourself comfortable that suites will be available where and when you want to go, late in the game.
The hotels are PH Seoul, PH Beijing, GH Bali. The dates are early to mid August, all on weekdays except the four days for the GH Bali encompass a weekend any info on the likely hood at those hotels? If not thanks for your help anyway. You guys have given me great insight.