I was considering a very similar lineup. I think it will work really well. I like the day blue of the Flamingo to complement the softer $5 relabel. I was also considering the Venetian $1 instead of the Bally's $1 so there are alternating 418 edge spots like the rest.
Another solid blue to consider is the Hard Rock Vegas $1. It’s just a shade darker than the Flamingo so the frac color would be different than the Bally’s spots. But I don’t think there’s a poker room at the Hard Rock so harvesting would be tougher.