In my (limited) experience, Indiana Jones and Space Mountain tend to get booked up the quickest on the DL side; for CA, I’d say Guardians and Webslingers. That said, typically nothing sells out for the day immediately; this time of year, most rides will still have LL times available to book until at least mid-afternoon.
Space and Indy are the most popular in DL. Toy Story and Guardians in DCA. Soarin and Webslingers can also sell out in DCA.
You can see LL availability in the app on the “Tip Board” even if you’re not in the park - right now everything is available for example as it seems to be a very quiet day.
Even on very busy days, there should be LL availability for everything until noon or so. And there are also cancellations if you refresh.