My first DHV was 1985. A flea marketeer from 1985-1996, on/off attendee 1997-2016, and then back as a flea marketeer in 2017 and this year. I believe the current location at Greene County Fairgrounds (GCF) is a remarkable improvement from Hara Arena.
Hara Arena was in disrepair in 1985 and in the subsequent years the arena degraded. I never understood how the arena passed code considering elements of the NEC (e.g. Mains power wires not in conduit stapled down the walls to outlets that where within the reach of the public). The parking lot where the flea market was hosted really deteriorated over the years and in some areas one needed to watch every step else a twisted ankle could be the result. Parking was another issue - free shuttle from the defunct Salem Mall (parking lot so-so) or paid parking at local businesses and residences. And the food from the arena left a lot to be desired to put in kindly. The pit area inside where the main vendors were located was quite tight quarters, challenging to see the displays and interact with the vendors, and ventilation at times felt non-existent.
DHV at GCF is spread out with a lot more room than Hara. Yes, there were issues in the first year (2017) especially on Friday with the traffic and parking issues. The rains also wreaked havoc with a mainly grass infield that is home to the flea market. Traffic had remarkably improved on Saturday. The grounds though did became a mud bath. I felt for the patrons using electric scooters - constantly getting stuck (as well as a variety of cars).
This year no visible issues with traffic or parking. As others said, grounded asphalt mixture was placed in the 'roads/walkways' within the infield. My understanding in talking with Steve in the Flea Market Vendor Trailer is that the Fairgrounds placed this mixture down on Wednesday - a day before setup. Perhaps if this was performed earlier the mixture may have had time to settle better. On Saturday (after Friday rains, foot and vehicle traffic) ruts and mud was present in many areas on Saturday. Straw was added to assist in controlling the soggy grounds. Saturday saw several rain storms interspersed with several periods of sunshine and increased temperatures. As Eric stated, it was manageable to navigate most areas.
I personally like the vendors spread across multiple buildings. The buildings are relatively close together. The larger buildings house the major vendors like ICOM, JVC Kenwood, etc. along with vendors like Universal Radio, HRO, and DX Engineering. Wide aisle-ways (except still quite tight when the heavier rains hit on Friday). Smaller buildings housed clubs, smaller vendors, etc. Te buildings are nice, well kept and maintained.
Food offerings are typical fairground types of food vendors. I found the vendors to be reasonably priced, decent quality in taste and portion offerings, very pleasant serving staff, and prompt service. In my opinion, an order of magnitude improvement from the captured Hara food offering.
One change - the pedestrian entrance was changed. According to Steve this was a directive from the Fire Marshall regarding not mixing vehicle and pedestrian traffic. Confusion on Friday as posted signs were directing people to this entrance - only to be turned away by hamvention staff and security. Personally my flea market location was along the fence near this entrance - when they closed the entrance to foot traffic it essentially stopped the flow to the several of us along the fence. I had to remind the hamvention staff and security that there were three of us along the fence - and they were stopping foot traffic. After that, they did their best to let people know there was a 'hidden row' but still little joy in sales (we all have different spaces for next year after meeting w/staff).
My recommendation - if you are at all interested and able to attend next year, do not hesitate.