Just fyi, keratin treatments are probably not going to give you sleek, low-maintenance, frizz-free hair. I have pretty dense hair with natural 2C waves and went through a phase in which I was getting keratin treatments (professionally) every 6 months or so. The attached pics are the results. In all the pics, my hair is air dried. It's still very poofy. It's very likely that with keratin treatments, you'll still need to blow dry and/or flat iron in order to get frizz-free straight hair. Ultimately, I was disappointed because it never really cut down the time it took me to straighten my hair, and my hair was still prone to frizz. If I flat ironed it, it did look relatively silky, but if it was humid or I got even remotely sweaty, my hair would poof out again. It did really loosen my curl pattern though, but that's about it.
That's not to say I think you should turn to a more heavy duty relaxer. The fumes coming out of my hair while getting the keratin treatments were terrifying enough!! I had to keep my eyes covered with a cloth, even though the salon would open two sliding-glass doors to vent the fumes. Also it took about 5 hours every time... not fun!!
I'm not trying to talk you out of it, I just don't want you to expect a miracle! (disclaimer: I also don't think anyone can expect miracles from doing the CG method, though my hair feels healthier and softer this way, and I am happier with it! It's really up to you and what you want out of your hair)