Here's my mostly uneducated take on the viability of these venues (mainly for my own entertainment). Only venue I've been to is U.S. Bank Stadium (for the unofficial state marching band competition). As for cities, I've been to Arlington, Houston, Atlanta, LA, and Vegas. Currently live near Mpls.
Overall -- for as much as I didn't like the stadium experience at Indy, I think it's here to stay unless Mpls/Atl/etc can offer a sweeter deal.
Arlington - I would imagine the overall venue and its acoustics would be an upgrade (provided the roof could be opened). Housing would be pretty easy too ... with the Dallas area being flush with large public schools. Biggest issue might be fan experience (Arlington is a giant suburb and the Stadium is surrounded by a sea of parking lots). I can't imagine this venue being cheaper for DCI either, considering there's never been a regional here.
Houston - Similar to Arlington: I think fan experience would be a downgrade from Indy. The stadium has a similar design to LOS, and the area is on the outskirts of Houston ... which -- IMO -- really isn't much of a tourist city to begin with. I can't imagine cost being cheaper either.
Atlanta - I'd consider Atlanta a small step-up from Indy: stadium is close-ish to their downtown, which has way more to do than Indy, at least. Based on the reviews here, the stadium's acoustics weren't much better than Indy ... but some of the sight lines are bad (the overall design of this stadium ... from its sphincter-like roof, to its circular design ... has never appealed to me). They already do a regional here, so housing seems to be good. Overall, I think I would have more fun in ATL than I did in Indy for finals.
Minneapolis - Total bias here, but this would be a step-up from Indy too. Way better nightlife. Way more to do in the daytime (Twins games, tons of breweries/distilleries, tons of gorgeous parks). Better public transportation (light rail can take you from Mall of America area to Downtown ... easy for those with kids). DCI MN at the college stadium was pretty much a regional in 2010/11 ... so housing isn't an issue -- The marching scene in MN is on the rise. The natural light ambiance of the stadium is gorgeous, but ...
... the acoustics suck. A small remedy: at the marching band show I mentioned earlier, the crowd was on the visitors side because of the tilted ETFE roof coming toward the home section. Unfortunately, the visitors' side doesn't have good sight lines, especially in the lower section (its more flat than the home side).
Another potential remedy might come after the 2019 final four, with the coming of an NCAA-required "blackout" curtain that could be used for noise dampening. Apparently natural light at a basketball game is a non-starter. I really hope the NCAA pays for this. Interesting read below:
Despite the acoustics ... who cares: Minneapolis > Indy. MAKE IT HAPPEN, DAN.
Detroit - This would be interesting. Can anybody that was there for the DCI Tour Premiere this year chime in on the experience? Detroit would have been a non-starter 10 years ago or so, but I'd imagine DCI could get a super cheap deal.
Glendale - Seems similar to Arlington ... a massive stadium/parking lot complex in the middle of a suburb. Also, AZ in August sounds awful.
New LA Stadium - The design is really intriguing: it's basically an ETFE "canopy" over an open stadium. I almost think this might be the design of the future (sort of wasted on LA since it never rains there).
That said: it'll never happen here since it's being built with private money. Also, the Rams owner -- Stan Kroenke -- is a heartless person who probably hates drum corps anyway.
New Vegas Stadium - Domed with retractable windows. The other interesting angle to this is that less than half of this is built with public financing ... which means we'd be more likely to see finals here than at the Kroenke Dome in LA.
Finals in Vegas? A man can dream ...
EDIT - let me be clear: stadium financing is usually nothing more than corporate welfare, benefiting some of the most awful of the awful rich. I still like to geek out about the design aspects though.