Hi there -- this thread is amazing. You've done a wonderful job identifying all these "Dallas" locations.
I am the president of falconcrest.org and have been cross-referencing various shows from that era to identify filming locations from "Falcon Crest". I am currently revisiting "Dallas" and wanted to share some information with you.
Please be advised my time stamps refer to the region 2 DVD release (PAL format) so in case you have NTSC discs, the time might vary slightly due to the 4 % PAL speedup.
In "Dallas" # 3.03 (as per original count) / # 4.03 (as per DVD count), the nightly establishing shot of the theatre (scene with Lucy and Mitch at 34:08) is a stock shot of the Wilshire Ebell Theatre at 4401 West 8th Street, Los Angeles, CA 90005:
In # 3.06 (original count) / # 4.06 (DVD count), the nightly establishing shot of the restaurant at 23:25 where J.R. and Sally Bullock meet is from Cheerio's, the former restaurant that used to be at the corner of Ocean Avenue and Pico Boulevard in Santa Monica, CA. It was closed in 1987, and the building was destroyed by arson in 1988. It portrayed the Tuscany Valley Inn on "Falcon Crest", which basically used the entrance only. The establishing shot on "Dallas" features the circular part of the building, which was usually visible on the left of the frame in the shots on "Falcon". You can read more about the use of this location on "Falcon Crest" in our "Behind the Scenes" section:
http://www.falconcrest.org/english/master.php?path=show/episodes/ai/bts/2/036:
I'll be happy to keep my eyes open if I discover more locations while rewatching the classic "Dallas" and will let you know.