You can spend your gold on all sorts of different things in the game, but most of them have limited value and then you're left without gold. The best option is to save up for the anvil, as it allows you to craft improved gear for your characters. That's a benefit that doesn't go away, so it automatically wins out over temporary improvements. The anvil is quite expensive, but keep in mind that while you save, you can also watch out for special promotions. In some cases, there will be sales that allow you to purchase the anvil for as little as half its typical cost. When you see a discount that works for you, make the purchase. Then you can start thinking about other uses for your gold, once the anvil is in your possession.