Lisa - I put a Thompson Elite on my road bike this year. I had to get one with zero setback because I have short femurs and I wasn't able to get the best stroke on the pedals. Thompson makes zero setback posts for a good price, so I bought it. Anyway... I like the post overall but I did have a hard time adjusting it when I first got it. I felt like I needed another hand to keep everything where I wanted it while I was tightening things up. Mine is like this in black. It has bolts in the front and back, not the sides. So when you tighten one down, it tips the seat that way and when you tighten the other one down, it tips the other way. It's like a seesaw until you get it tight enough where it will stay where you want it. Of course, you have to watch and make sure it doesn't wander front or back too at the same time. With my old post, I could hold the seat with one hand and tighten it down with the other and go zoom. If I had to do it again, I wouldn't. If you can go play with one at your LBS before you buy it, that would be my suggestion.
A friend at work has a Bontrager X Lite and it's sweet. One bolt straight out the side, very easy and fast to adjust. It's carbon but I don't remember if you are getting a steel bike or what this time.

Sandra - so you say you have a smaller mixte you may want to sell? I have a 29" inseam. I'm just sayin'...