This is a thought inspiring post commems ... my views as a collector FWIW ... apologize in advance if I get too long winded with the reply.

Quick background ... I live outside Baltimore, MD and have available in the local area multiple small and large coin show opportunities.
I attend perhaps 4 to 6 small shows (<30 dealers) every year ... and try to make all three Baltimore Whitman shows (>300 dealers) plus one major national show every year.
My collector strategies are different for each type of show ....
Small ShowsI agree with the wise comments you posted above. Everything you stated matches with my boots-on-the-ground reality.
My general attitude for these small shows is a relaxed day with minimal advance preparation, nothing to sell and no pressure at all. Fun in other words.
Most of these small show dealers are interested for survival reasons to sell items more popular than the commemorative series. I find few commemorative and, in general, they are as you stated ... high AU through low MS of the common coins.
That said ... IMHO these small shows are the very best opportunity to develop honest relationships with the same local dealers that you will see over and over again ... and over time those relationships will hopefully lead you to a great coin they come across.
On my 'small show' circuit I continue to see about 80% of the same faces every time ... and all of them recognize me now ... I've purchased a few things from most of them, and all of them know of my interest in MS and circulated classic commemorative (as well as the many other sets I am pursuing).
This personal connection developed over time with small show dealers has led to several of my most satisfying coin purchases ... thrilling when the local dealer says "Hey Dave, Great to see you again ... I found this for you and know you need it".
Small Shows ... casual day of fun and develop long term relationships.
Large ShowsLarge shows are where I go to sell and politely prowl the stock of numerous unknown (to me) national dealers. Large shows are also the very best opportunity to view in hand and purchase coins that meet your exact needs.
This can be an intimidating place for a newer collector ... the sharks are in the water and they are looking for meat.

My strategy here is significant advance preparation ... I'm bringing coins to sell and expecting as well to buy ... and have done the homework to recognize current market prices buy/sell on everything.
I have with me all my Want Lists with current CDN Bid/Ask prices ... and have looked in advance at the show web page to identify the most likely dealers to approach.
Fortunately, over time relationships also come into play in this large venue ... and there are some national dealers (3 to 4) who specialize in commemorative who I have become acquainted with on a first name basis ... but in general the bourse is filled with folks who do not know me.
I visit my known dealers first ... complete the buy/sell ... and then make a very quick trip through the bourse stopping to inquire at each likely table about the coins I am interested in ... always polite ... never interrupting another sale ... but somewhat aggressive in my approach.
No doubt I have had the greatest success at adding new coins to my humble collection at large shows.
Large Shows ... Advance Prep ... Work not as much Fun
Geepers ... reading above ... much more than anyone wanted. Tempted to just delete this reply ... but hoping you accept my views as an interested fellow collector sharing my experience.

David