My advice is to use the Gerber cotton training underpants. They are THICK and absorbent. You will still have to change their pants with big accidents, but hopefully not have to clean your carpets! Another tip that's helpful with this method is to put a potty in the area that your kids are playing (playroom, outside, basement, etc). Then, when they're ready to go they can get on it quickly, and it's right there visually. When my daughter was 2 1/2, she'd been "ready" for a long time, but was still asking to wear diapers. I basically told her, "Mommy is not buying anymore diapers - it's time to be a big girl and wear big girl panties". Then, I removed all diapers from the house (only used pull-ups at night and naps), and put her in big girl underwear. The day I started this, I made sure I had NO plans for the next few days - and nothing major for a few weeks. I put a potty in our playroom. It was late spring, so at times, she was completely naked from the waist down. I can tell you that she pitched a fit the first time she had to poop, but I just kept verbally encouraging her to go on the potty. She screamed, but she did it on her own (I didn't force her to sit on the potty) and was fully trained within days after having that first success. She had one pee accident, which I calmly told her we'd have to clean up TOGETHER, and that I knew she was a big girl and could go on the potty next time. No scolding. She's my first and I was shocked by how fast she was potty trained. I highly recommend the "bottomless" method!
Good luck!