This is all I’ve been able to find, most from years later:
https://starwarsblog.starwars.com/wp-content/uploads/sites/6/2015/10/EpicCollections.jpg
http://chinese-starwars.com/jediarchive/expanduniverse/donald/donald/24_captain_pellaeon.jpg
http://www.battlegrip.com/wp-content/uploads/2015/03/expandeduniverse.jpg
I’ve seen a few of those before (I even own one of those Thrawn figures), but the weird thing is that I’ve seen plenty of EU (and Thrawn trilogy) related ads from the mid- to late-90’s, but nothing about just the book in 1991. I mean people must have had some way to get hyped for it, so there must have been some promotion for it.
It did remind me of this commercial, though:
https://www.youtube.com/watch?v=bOV2dGdFbGk
It’s a bit funny really that one of the most beloved SW books never got a proper TV ad (to my knowledge at least), yet one of the more controversial ones got a dramtic TV commercial narrated by Mark Hamill.
I think there were full page ads in magazines like Starlog at the time.
Yeah, that makes a lot of sense. I’ll have to see if I can find some photos/scans of Starlog from 1991. Though, I still think there’d have to be more than just that.