Join Date: Jun 2005
Location: Charlotte, NC, USA | CLT, formerly LHR & AMS (with just a bit of PSP)
Programs: BAEC Gold, Hilton Diamond, BonVoy Titanium, (soon former) Caesars7*, (former) Wynn Black, HR "Icon"
Posts: 8,172
I've personally used the email alerts to help clear my wife on B or Y fares into Z (using miles) on NWA from AMS-BOS multiple times in the past year.
The convenience, and the fact that I know when availability is there --- is worth it alone. (and the value helping to clear a 15K mile upgrade from Y to J is worth the annual fee, IMO)
I've also used it to check up on Delta V buckets, but more so, as a curiosity.
Be aware that V bucket information can be a bit flaky, you often have to "request" the specific V bucket information (for DL) on your routes/flight searches.