Wal.
When you get there you will see just how well-organised and laid-out the Oshkosh venue is, (lay-out designed by aircraft enthusiasts for aircraft enthusiasts). Knotty and I had no problems getting photos and nor did and our closest 500.000 friends

Case in point:



For interment close up photos of some truly remarkable aeroplanes I would suggest that you be on site at opening time each day. We found that the first hour or two each morning the airfield was pretty sparsely populated and this presented ample opportunity to get up close and personal with the aeroplanes.
Case in point:






The "souvenirs" I was referring to were things like shirts, caps , cups, programs, vids etc. These items tend to be date-specific eg "Oshkosh EAA Air Venture 2015", so by the final day most vendors are keen to off-load at very reasonable prices, (and I am led to believe that Reno is the same).
One other thing Wal.....it maybe very hot, so wear comfortable light cloths, take a good hat, sunnys, and lots of sun screen. I found though that sitting on the grass in the shade of the wing of a C-46, P-51, or B-17 was a most relaxing, atmospheric, and comfortable way to watch the daily air show
TOR
PS: don't forget to visit the temporary sea plane base on Lake Winnebago just down the road from the main Oshkosh venue.....very worthwhile indeed. You can catch a regularly-timed shuttle bus from the main airfield all through the day.