Where I believe everyone needs positive feedback to reinforce desired behaviors, I also believe when it is offered, a self-assessment question to the receiver should be asked first.  For example: "Wow, now that the meeting you conducted is finished, how do you feel about it?"  If a person feels a lot differently than you do about the outcome, it may be best to focus on that before offering your praise.  Praise can actually de-motivate people if given when they feel they could have done more to prepare or have ideas they want to try to improve their future actions.