I went with the 128gb 10.2” per your recommendation. I also got a Speck balance folio case (black) on sale for $21 set for curbside pickup tomorrow at the same location. Total was $500.21 for both items.In terms of bang for the buck a 128GB 10.2 iPad is a better buy than a 64GB 10.9 iPad Air. You should save about $200 which would more than cover the cost of a decent case and even AppleCare+ if that interests you.
I would recommend the 10.9 Air mostly if you want something like the Pro without paying extra for one.