Simcity on the SNES is fantansic but there's so much room for improvement that I find myself zoning out and daydreaming about features whenever I'm waiting for the taxes to be collected...
Vanilla changes I'd love to see (AKA "Game is great, don't break it"): a couple more save slots, additional scenarios (including the PC's Dullsville and Hamburg scenarios), landscaping options (plant forest, dig/fill lakes and rivers), maybe a map editor and mouse support.
Shoot to the moon changes that would blow this game out the water (AKA "Let's take a page or two or ten from the sequels"): more type of roads, add education, healthcare, entertainment, parking space, garbage, sewers and water management to the needs of your citizens, complete overhaul of the gift system so some of the gifts (big parks, zoos, amusement parks, libraries, casinos, police/fire HQ, train stations) can be purchased normally, add military bases, farmland, mining, oil, forestry industries so your cities go from flyover state all the way to ginormous metropolis... I could go on and on, the list just never ends.
Another idea is to make the 1UPs found in Zelda II increase the starting lives count as well as incrementing the current life count.
That would have been cool, that's how it should have always been
Also, color version of the GB Mega Man games? Yes please!