Lindy - first, let's ask BobD to change the title of this thread. There are many members on this message board that have excellent info on shows and galleries. So let's not limit the input that you can receive and really open this question up ...
At 12% commission (which is just above illegally dirt cheap in my opinion) would mean that for every $100 sale you are paying $12 to the mall. So $10,000 worth of sales would equal $1200 worth of commissions. At a $1500 entry fee for the other show I am calculating $12,500 worth of sales ... that's an outrageously huge amount of key fobs to cover your fee.
So you are looking at a situation of the Show costing you a defined amount of $1500 or the Mall costing you at the least $12 ....
Now, I will state that it has been nearly 15 years since my last show ... I loved them but my ankles just gave out from years of walking the tables. But 15 years ago I do believe that a $3000 to $4000 take on a large show was a good return. Now that is also when gasoline was well under a $1 a gallon and home prices for nice big tract houses topped out at $125,000. That also was a time when I was very well known in my selling area, I was not a
New Artist" just starting into the market with no name recognition.
So on this point I would go with the $12.00 Mall space and make sure that my key fobs were priced at $15

That way anything I sold at least bought Mike or I a cup of coffee and a donut.
My next thought is the fee scales, in my opinion, show the confidence of the show managers. The commission fee implies to me that the Mall has confidence that you are going to make sales ... enough to justify such a low commission. When you think it through you and I both know they need way more money from you to cover their space, electricity and advertising ... so they are fairly sure you are going into a selling market. They are very invested in your making lots and lots of sales.
Edit: A quick note here from the first thread. This investment in sales by the Mall is also a great point for going into Galleries. Galleries are totally dependent on selling your art for their income. They make no money unless you do too!)
The set fee Show, again just to me, implies that they don't care whether or not you make sales or whether they can bring you buying customers ... they got their's up front so have no investment in how well you do! If you have a bust they still got their money ....
Another plus for the Mall ...
Do your homework ... Check if either the Show or Mall are a regularly scheduled event? See if you can get a copy of the advertising fliers for the last several years for these shows. An easy way is to go to the library and riffle through the local news papers for that town or city. You are looking to see if they are advertising a little or a lot, when the advertising comes out, are the ads well enough in advance so that your customers can plan to attend or just on the day's the show is actually being held.
Also look for artist's names that you could contact for shared info.
OK ... no you don't want to call the Other Pyro artist or another carver as they will clam up because you are competition. So try a Potter or Wheel Wright/ Blacksmith or Quilter ....
Shows that are advertised in advance give customers a chance to hoard their money and plan to attend. Regularly scheduled shows mean you will be pulling against an already conditioned to buy clientèle ... repeat - return customers. Short ads (the day or weekend of the show) mean impulse buyers so your sales potential drops dramatically. If I know there's a show in two weeks I start stashing away my mad money for it. If I discover a show is being held this weekend I only have what is left in my pocket at that moment in time.
Mall shows are indoor and in late November that is a huge plus because very cold customers keep their hands in their pockets to keep them warm. Warm comfortable sheltered customers have their hands out of their pockets and on your wares or in their wallets ....

Rained on customers just go home.
Edit: I don't know about where you live but people where I live, the Baltimore-Washington corridor, go directly to 7-11 for toliet paper if there is any hint of snow in the forecast .... If we were talking about Spring scheduled show dates I might tend to the outdoor show instead because everyone is so ready to just plain get out the house and enjoy the spring air.
You do need to include the cost of your attending either show. What will it cost you to rent a room, gasoline, food, do you need to hire a pet sitter for one show but not the other. Can you camp out and mooch off of your third cousin or is it going to cost more than you can possibly see in profits to 'get a room'?
(Oh, Susan, you had that nice New Year's resolution of no more Epic-mails ... think I need to go to a new window for more ... )
Susan