I would make a huge bon fire and put in all the Barrows stuff
Then, I would make everything drop less dragon items and stop Dust Devils from dropping the chain.
I would make rares untradable, and if you die, you can get them back from...Someone...
I would make a masters guild. 200 quest points needed, and must have done recipe for disaster, legends, and MEP2. You could buy a Masters ammulate for 5k once you finish quest (A bit better than Onyx).
I'd make it so it hid combat levels. It is so annoying when someone in F2P is like "ZOMGF!!! Loser!!! Get a life!!!". And it isn't needed, except in the wild and dueling arena. Maybe we could keep the color.
I would make it possible to actually get a mime more than once a year.
I would remove the evil chicken.
I would ban a certain person (no one at RSBandB, just some loser I used to know).
I would fix the censor so it actually serves a purpose.
I would remove the pure ess.
I would make it so you had to have some skills to enter some places (20 woodcutting, and you could cut the vines to open up varrok, 50 fire making to burn a hole in a wall to Ardgounge, 30 Herblore to make an explosion to explode a hole in the wall I would add to Sears village, adn other stuff). This would help the autoing problem, also. Same with merchants who simply don't understand that they could actually get up there skills
I would add a bank in Lumbridge.
I would make banks smaller.
I would fix it so RSC could be played by anyone.
I would make more stuff in the Elven lands. They are sweet, but there isn't much to do, besides Lletya.
Create a RS lottery. 100gp per ticket, winner gets all of the money spent on tickets. Happens once a month.
I'd make it so you could set a price for some items, and when you were trading it, and someone examined it, it would say "Redfire50000 requests 50,000 coins for the Dragon Dagger (s)" or any other item. Also, that would be the price that determines what you keep when you die.
And some other stuff.