The choice to co-sleep in quite individual and everyone in the family has to want to do it for it to work successfully. Don't feel like you are a bad mom or abandoning your child if you don't choose to co-sleep until your child is 3 years old.
I started out co-sleeping and am certainly not against it in any way. If it works for you and your family, great, if not, you have the right to try and change things.
Personally, for me, I got to the point that I was so exhausted that I was having a hard time being the best mommy I could be during the day. The lack of sleep started making me depressed, easily frustrated and hypersensitive. I decided that my being able to sleep for even short periods of time at night was the most important thing if I wanted to fully give myself to my son during the day and enjoy our time together. Now, I still nursed during the night until he didn't need or want to anymore, but he was sleeping in another room which allowed me to fall alseep fully inbetween feedings. My husband also helped out by going to get our son when he woke up and putting him back in his bed after feedings.
Our son was one of those babies who needed to cry before going to sleep. That said, I was not comfortable with the cry-it-out method. We tried it a couple of times, but I just couldn't handle it and would go and get him after only 10 minutes or so.
A friend of ours lent us a book called 'The Baby Whisperer' and it had some great advice in it. The author, a midwife, suggests staying in the room with your baby, next to their bed (progressively moving further and further away from the bed) until they are fully asleep. Her advice is to soothe them in your normal way (rocking, nursing, massage, etc.) until they are drowsy and then put the baby in bed. If your baby starts to cry again, then you pick him or her up and soothe again until they are calm. As soon as they are calm, you put them back in bed again. You might have to repeat this many, many times in the beginning, but the theory is that, eventually (she says in 3-7 days), your baby will learn to self-soothe and fall asleep alone, all the while knowing that mom or dad are there when and if needed. She also mentioned that it is a good idea to not talk or look at your baby during this time, thus reinforcing the idea that it time to sleep and not play, nurse, etc.
This method worked fairly well for us and, while initially more tiring, it was less stressful than the screams and tears. I felt better knowing that my son wasn't all alone in his room, scared and upset, and he learned that we will never abandon him.
Whatever you decide, listen to your instincts. If crying it out doesn't feel right to you, don't do it. If co-sleeping doesn't quite work for you either, don't do that either. There are compromises and I hope you find a solution that works for you and your entire family. Good luck!