I use a ceramic flat iron the brand is HerStyle.  I paid a pretty penny for it, but I love love LOVE it especially now that I wake up with bedhead.  It is a thin flat iron so if I want to give my straight hair a little curl when it is longer I can....although I learned I am not very good at that yet.  It gives my hair a nice polished look.
I've used rollers and irons for so many years trying to make my hair something it is not.....curly.  I had better luck with hot rollers and feel they are less time consuming

Hey Rach, as for the curling iron vs. hot rollers, it kind of depends on what you're going for. They tend to give different results. I have curly hair and I "straighten" it on hot rollers. I put them in fairly haphazardly (but be sure to comb through before wrapping your hair around the rollers! otherwise you get a giant mess), leave them in for about 10 minutes, take them out, and then just shake my hair out. I get lots of body with a little bit of wave. When I wear my hair curly, I'll often fix a couple of front pieces using a curling iron to make my hair look a bit more polished... curling iron curls are much neater than my natural curls. I use a 1/2in barrel to make tight-ish curls that blend in with my own texture.
So I'd say small barrel curling iron if you're looking to actually make your hair curly (but be prepared to spend a long time doing it!), and medium sized hot rollers if you're looking for lots of body and wave (aka sex kitten hair).
Of course, there are also really fat curling irons and really small hot rollers... the really fat curling iron is good for getting some wave going, or even some really loose curls at the ends of your hair, but not so good for body because if you start at the roots, the curling iron might flatten the roots, just as a straight iron would. The really small hot rollers are good for a loose curl, but only if your hair is short enough to actually wrap the length around those little curlers.
Did you also know that you can curl your hair with a straight iron? Search for tutorials on youtube.com, it's really quite cool. I think GHD recently made a straight iron that had smooth edges so that it's easier to use it to curl if you want. Very versatile, but it wouldn't work for my fine hair. I'd end up with really thin-looking hair.
On the topic of CHI, I just bought their hairdryer... and then promptly returned it. It did nothing for me. My $20 Conair did a better job. It didn't really seem to dry my hair any faster and it seemd to flatten my curl! Grrr! It seems like it would be really good for someone who wanted to straighten their hair, but I don't blowdry when I "straighten" it. I just let it dry naturally and then use hot rollers. So then I bought the Revlon Tourmaline hairdryer (basically the Revlon version of the CHI) and I really like it! It was only $30 and it works great. It has fabulous reviews on drugstore.com, too. Ok, I'm done with my unsolicited and slightly off-topic opinion of hairdryers!
p.s. I have really fine, curly hair that comes down to about my shoulders right now.

I'm a sucker for expensive products, so take the rest of what I say with a grain of salt.  And I don't flatiron.  But I will say that back when I was blow drying my hair regularly, I invested in a professional hair dryer (Solano brand), and it made the job so much easier.  I have also heard that the pricey ones last a lot longer than a cheaper appliance would.  So if you can afford it, go for a professional one, just read reviews first.
Nevermind--just realized this is an outdated thread...and that the thread was revived by someone obviously spamming the forum with reviews of a particular flatiron...