I wanted to share a thought. 9 months ago when I decided to ramp up my mileage collection, I thought I'd have to use one of these services because yes, the search process was daunting. However, since then I've learned an awful lot, and now feel competent to do it myself. You need to read FT and know the nuances, you need a search tool like Expert Flyer or KVS, and you need some patience.
I'm not at all putting down the use of paid help, if you don't care to go through the learning process it can definitely be worthwhile, and if you only book tickets occasionally and/or have miles on multiple alliances such that you'd have to learn the search-and-destroy, er sorry, search-and-book procedure for multiple alliances, it's likewise a better decision to pay than to learn yourself. I found the learning process informative.
Another thing is, I don't know how the paid services work, but I assume they limit you in terms of tradeoffs of time and routing. I just booked a trip for my wife. I assume you can tell an award service "I have miles on Skyteam and Star Alliance, I want to go on these dates, I have this much flexibility, and I want this class of service." When I booked the trip for my wife I had a huge number of tradeoffs. Book now on a decent routing or wait for an ideal one. Book with Star Alliance miles, which are the easiest to use, or Skyteam, which are the hardest, and save the *A miles for later. How much better is business class on the A380 than on the 777? Leave at 7AM and connect once, or leave at 11AM and connect twice? Not to mention that I didn't have enough USAir points to book a certain trip I had my eye on, but was expecting some to post shortly, and then just saw a promotion that allowed me to buy the last points I needed. If you can do it yourself, you will have a lot more flexibility.
Again, I am no way criticizing the decision to use a paid booking service.