Springfield Heights buildings (level up buildings)...do you store all of them or keep some?

I still can't believe that the hardest to max-out building collection (business centers) are only worth 2%. You'd figure they'd have the biggest multiplier.

Anyway, for anyone who does mystery boxes, storing the private islands, condos and business centers should be relatively easy. Swap them out for I&S signs and news vans until they're all gone so you don't decrease your multiplier. You save space and increase your $$$ multiplier in the process.