One thing I'll add in here - I'd be less put out by lounge charges if it was "access across the current one-way trip/access across the day*" rather than "per access". While some of my airline craziness is self-inflicted, the number of times I've gotten stuck dealing with dubious re-routes and so (e.g. two "blue sky" canx in the last six months alone) on are not trivial and the idea of being socked for a second fee/two "credits" grates on me (especially since that could trigger a one-hour layover [no lounge visit] turning into a six-hour layover [lounge visit needed, especially since a trip to a help desk in there might be merited]).

*Basically, I'm thinking "across the day, but if you get bumped/IRROPS-ed then the ticket the next day is covered as well" or "once the IRROPS tool goes live you get access if you have the relevant card". "The last flight of the day got screwed up" is hardly an unheard-of situation, and I don't like the prospect of the airline effectively profiting off of a failure to deliver on their timetables/advertised service. A case in point would be the meltdown on MSP-YWG back in July...I almost wound up with a two-day delay there because of repeated cancellations. The idea of being socked with three lounge access fees/credits because DL repeatedly told me I'd be able to get on a flight that day and then failed to run the flight(s) in question is absurd.