I used a copper IUD for 6 years with very few problems, then had two more kids. I wanted to avoid any hormonal options, because hormonal birth control kinda makes me psycho. :) For me, the only side effect of the copper IUD was slightly heavier periods...but nothing I couldn't handle.
Don't get your tubes tied unless you're absolutely sure...and it sounds like you're not. And try to make peace with yourself on the need for birth control! There's nothing wrong with spacing out your pregnancies - it's better for your family, your finances, your sanity, and your own health!
I completely agree with Vicki (above) regarding the snipping vs. tube tying. I went with my friend when she had her tubes tied, and she was really miserable for like 2 weeks after. My husband just got snipped (now that our family is complete), and he was just mildly inconvenienced for a few days. And now we're free!!! It's fair that he should be willing to do that - after all, you had the babies, and the pregnancies, and took care of the birth control for all these years.