I was thinking about doing a few offers and then canceling right after I use the coins, but I'm trying to decide on the best room that gold can buy. By best, I mean the quickest for making the most amount of money.
If you can afford the piano room at 350 gold its a great deal paying 1 million/3 hours. If not, the neanderthal in the museum is only 90 gold and gives 300k+ every 6 hours. Of course, if you wait for a 1/2 off sale, then they are both really great deals.