The "moving venue" is, in my view, an excellent approach. As Kevin mentioned, attendance at the convention can be built in to the "family summer vacation". Wife and I have visited all fifty states/state capitols/multiple National Parks and Monuments, State Parks, beaches, mountains, prairie land, and historic sites of all kinds as we travel to and from a Nats. This is a definite advantage that the current system has over a permanent and fixed location, or even two or three fixed locations.
I would suggest that having a fixed location would result in the need for the hiring of a professional staff to plan and execute many of the administrative functions at a convention. Some immediate effects would be
1. conventions become more expensive with higher costs being placed on the attendees, and
2. a huge burden being placed on the nearby IPMS Chapters who would, year after year, be called upon to provide staff to run the convention activities.
3. Fewer participants would attend from those areas farther away from the convention, an issue that we currently experience, but that would be multiplied year after year as those out-of-towners loose interest in returning to the same city, or 2 or 3 cities, year after year.
4. I don't believe any research has been done in this area, but a sedentary venue would most probably result in a concentration of attendees within a single day's driving distance from the event, and an unintended concentration of winning entries from that same radius of attendance. Over a number of years such an issue could have a very negative impact on IPMS.
The current system allows for any chapter, in any part of the country to offer a bid for one of two convention dates, either two years out or three years out.
In many cases, bid preparation results in a number of chapters working together, leading to cooperation in other areas among those chapters in issues not related to a bid.
The current system creates opportunities for attendees in the nearby area to volunteer their time during the convention, serving in staff positions. The fact that the convention will rotate to another part of the country means that these volunteers will not be expected to serve every year in these roles, and that others who cannot travel long distances to conventions will have the opportunity to serve on staff.
The current system does not favor those living in an area that is close to the convention site year after year, benefiting from lower transportation costs. That particular happenstance rotates through the IPMS population due, in fact, to not having a permanent location.
Clearly, my personal preference is to continue the current system which allows for bids from any chapter, located anywhere, relying on the Host chapter(s) to plan and execute a successful and enjoyable convention. And, at the same time, providing attendees the opportunity to visit a part of the country they've not visited before, or visit that part again due to the variety of sites and activities which call for a 2nd visit.
I'm very much looking forward to going to the Chattanooga Convention in July/August of 2019. Wife and I have not visited Nooga and we've already got a list of places to eat and things to do on our way there, while on site, and on the way home.