I try not to blow dry my hair too often. And I usually only bust out the curling irons for special occasions or if my hair already has some curl to it because I a) scrunched it or b) put it in a bun while it was wet.
My flat iron gets the most love and attention, whether it's to smooth out my whole head or just tame my bangs and the shorter pieces of my layers into submission.
When I first got my flat iron, I got the CHI 44 Iron Guard Thermal Protection Spray (8.5 fl oz for $13). It was my first foray into heat protectant sprays and I didn't really know what to think. I quickly found out that CHI was kind of sticky. It also had a weird smell. I finished the bottle, but quickly went in search of another product.
I told my stylist about my CHI woes and she recommended that I try the Matrix Vavoom Gold Heat Iron In Control Protective Dry Mist. For another $13, I got another 8.5 fl oz bottle and gave it a go. The smell was much better with Matrix (I'm a fan of their various shampoos/conditioners, though, so I wasn't really worried) - one of those "professional salon" smells that doesn't linger very long. What I liked instantly about the Matrix one, though, was that I really thought it made my hair look shiny. Not greasy, but healthy and kind of glossy looking.
But... what about when I blow dry? Matrix didn't market this product for blow dryers, too (although, I'm sure it wouldn't hurt), so even though I was happy with the results, my fickleness kicked in and I wanted a product that protected my hair no matter what heating element I took to it. I finished my bottle and then kicked it to the curb in search of something better.
My search led me to TRESemme's Heat Tamer Spray. $4 gets you a bottle with 8 fl oz and a cool trigger-looking sprayer that I found much easier to work with than classic pump-sprayer of the other two bottles. Of the three, TRESemme's smells the best. It's not overpowering, but it is a sweeter smell that may bother some people. I like that it didn't leave my hair sticky and that you can use it for blow drying and curling and flat ironing ... and anything else you feel like torturing your hair with. I don't know if it's the best on the market, but so far it's working pretty well for me and I'm almost out of my first bottle. Unless I stumble across another multi-purpose heat protectant, I'll probably end up repurchasing this one.