These suggestion both have to with Multiplayer. First I think that when one player buys a bag upgrade then the other players should get it to. Although I still think it makes sense not to be this way. If not allowing players to share a bag upgrades then maybe reduce the cost of bags in multiplayer. Currently if I have 4 players then getting all the bag upgrades for all of us will cost 48,000G. I think cutting it down a little (24,000-36,00 maybe?) and still having everyone having to buy it for themselves would be the best idea. The other thing I think would be cool if done is to let us do Multiplayer Prairie King at the arcade machine! I could imagine this wouldn't be to hard to add in because we already have the event with Abagail. I'd make it so you can't get the fector's challenge achievement since I can imagine it could be easy to steam roll everything with 4 players. Along with this I think players should share lives.
Me and my brother were thinking the exact same thing about the multiplayer prairie king, I hope it gets implemented!