Gulfstream International Airlines - December, 1995

Gulfstream International Airlines operated from 1988 to 2010. The airline primarily operated codeshare flights for major airlines. In December 2010, the airline went bankrupt and its assets were sold. Silver Airways launched as a new regional carrier with assets from Gulfstream.

https://en.wikipedia.org/wiki/Gulfstream_International_Airlines

Trans World Airlines (TWA) - September, 2000

This is most likely one of the last timetables from TWA. It's too bad, really, because they were operating well towards the end. I posted one of TWA's last route maps here. The one below details the TWExpress and TWConnections flights. Also, you can see the timetable says that TWA was setting up a focus city at LAX. The other focus city was San Juan while JFK was considered a hub.

"The Legacy of TWA":

United Airlines - July, 1995

This timetable stands out for one thing: a total lack of marketing expertise on the part of United Airlines. Shuttle by United was a competitive response to Southwest's buildup of service on the west coast, and yet this timetable manages only to put a logo on the front cover and bury the details of the service on page 13.

The timetable totals 512 pages and there's not a single ad for Shuttle featured. However, three pages were dedicated to cargo information, including cargo container specifications.  I haven't seen that in any other airline timetable.

The Los Angeles Times wrote a great article about Shuttle vs. Southwest.  From the timetable, here are samples of a number of weekday flights in key Shuttle city-pairs:

SFO-LAX: 38
SFO-BUR: 12
SFO-ONT: 12
SFO-SEA:12
SFO-SAN: 11
LAX-SFO: 41
LAX-OAK: 14
LAX-LAS: 12
LAX-PHX: 12
BUR-OAK: 12