Are you trying to lure people in with bait (VLC)? ;)
I won't argue, and if people vote for Volgograd, I'll go to Volgograd, but I think St. Petersburg looks more interesting, and the heroic world is better represented here, and I'll modestly keep silent about the cultural aspect. :)

In terms of cultural attractions, St. Petersburg can give anyone a 100-point head start. But it's unlikely that people will rush to museums, Peterhof, etc. during the tournament. The weather in St. Petersburg at this time is unpredictable, while in Volgograd, 99% of the time, beaches, volleyball and football will be available, and you can have barbecues in the evenings without fur coats and felt boots, etc.
P.S. Although I shouldn't have mentioned felt boots, I hope Monsieur Valenok can find time for the event.

Bert will provide more details on prices, but I can say that during our visit, we stayed at a very decent tourist center, and renting a cottage for 6 people with breakfast included in the restaurant cost 7K per day.

Regarding travel costs: an extra-economy option is possible, using Muscovites' cars as taxis.