Playing catch-up, so here are some of my thoughts. I would love to believe that Liara will play an important, substantial role in ME3, and events in LotSB certainly do point towards this being the case. I have no problem with her not being a squadmate, and believe that, if done correctly, her role could indeed be very satisfying. Even more so if her Prothean expertise is going to come into play. However, my only concern with this is if she was reduced to merely 'quest giver' a la Admiral Hackett, and little more. I realise that this doesn't seem very likely given the potential set-up in the DLC, but it's a slight concern nonetheless. Maybe I have my pessimist's hat on today! I should just be glad that she's at least guaranteed to be in the game and see the glass as half full. Fans of other characters may not be so lucky. So taking the hat off, I'm also of the opinion that she'll likely join the squad at some point near the end, leaving Feron in charge of the SB network. A bit too much of a coincidence that he's already got some experience in the info trading business, and is now camped out at the base looking for something to do.
I would also love it if she could have some kind of interaction with Aethyta. If BW decided to follow the pattern of the previous 2 games and give squaddies a side mission of sorts, then a meeting with her father could potentially be Liara's (even if she's not technically a squadmate). However, if her role is tied in with the Protheans, it may be that she'll be too busy with that side of things and a side trip to Illium may have to wait until more pressing concerns are dealt with. I tend to agree with what some others have said - that it would be great to see, but I'm not sure it'll happen. Hope to be proven wrong.
As far as my choices re: when to play LotSB. I prefer post-SM for many of the reasons already stated. The Reaper threat is more severe than the Collectors, and Shepard returning is up in the air at that point. Also, as a player I like to have the DLC to look forward to at the end of the main game. My Shepard also feels like she needs to take care of the current threat and wants to get Cerberus off her back asap. She hates those f******. So, as far as I'm concerned, she doesn't receive the SB intel until the end. She responds that she's frustrated, because that pretty much hits the nail on the head. She's fed up with Cerberus and the Council's stupidity, and hurt over Horizon. She's not a happy bunny

jlb524 wrote...
I've gotten into disagreements on how much this 'vendetta' against the Shadow Broker still motivated Liara in LotSB. I wonder what others opinions on this are?
It seems as if the vendetta was used as the main reason in ME2 for her actions, but was then changed in LotSB, where it became more about repaying a debt to Feron. If she was able to take out the SB at the same time, great, but if not..."Get in, get Feron, get out...and kill anyone who tries to stop us". Then she mentions something about just getting Feron, and again at the end says all she wanted was to get Feron back. Her key focus seems to be to get Feron above all else. He saved her and Shepard, she needs to save him.