I'm pretty new to CP and I've had some time to kill so I went through a bunch of this thread (jumped from about page 25 to 60 though.)
I like the idea of a joint stadium for the Stamps and Flames (and MLS in the future.) As such, I also think that the re-development of the UofC lands which currently house McMahon Stadium, Norma Bush arena, the athletic park, ball diamond, volley-dome and tennis courts would be a good location for the new stadium. I think opposition from the surrounding communities would be a big hurdle though. The area has a number of pro's and con's. LRT access is good, but traffic flow can be quite bad (based on current Stamps games.) It is outside of the downtown core though.
One concept that I have in mind that could be somewhat interesting (maybe not technically feasible) would be a stacked stadium situation. Essentially, you would bury a lower dome under the football field level which would contain the NHL ice surface. You could try to configure the field seating such that it would provide sight line to the ice level via a moving or opening floor.
Another idea for additional suites would be to put a set of suites at ice level. They would be configured similar to the current suites at the Dome with two or three rows of seating and a suite behind with lower bowl seating rising above the suites. The new AT&T/Cowboys Stadium has that type of configuration and I think it would be pretty cool for hockey.
With regards to site selection I wonder if anything could be done in the west Bridgeland area? If the land could be purchased or annexed the area north of Memorial and east of Edmonton Trail seems like a good home for a sports complex. LRT access is available plus there are various rumours and thoughts that a North LRT could potentially run up Edmonton Trail. The land provides easy access in and out of the downtown core and the road infrastructure is reasonable. The new bridge from East Village would obviously allow the future, dense population easy access to the facilities. The area is growing in trendiness and a stadium development would probably really help the area from a retailer/entertainment/commercial view.
Maybe Eau Claire mall would be a good place for a stadium. The location would be pretty ideal although you'd really be limited to just building a Saddledome replacement due to space. There wouldn't be any room for surface parking either so the organization would have to look at building underground parking. Eau Claire needs some life and I've seen a re-development plan but I doubt that will happen.