That 21 qt is what I started with... and I am still using it 4 years later.
If you follow the "typical" progression, the next thing you will find is that the wife or significant other may start complaining about the kitchen time, and smell.
What I did was invest in a turkey fryer setup. The aluminum pot works great for all grain and full wort boils with extract, and the burner allows me to brew outside.
Enjoy the pot, and if you think of it... cover the oven top in foil (leaving a hole for the burner) that way if you have a boil over the cleanup is easy.