I have a comment regarding SMD. Over the last several months, I have grown to really like SMD parts for homemade boards.
I've found that they are not as hard to solder as you might think as long as you stick to the "bigger" SMD packages (SOIC chips and 0805+ resistors/caps). There's some really good tutorials out there. SMD components will obviously save you a lot of space on the PCB. For 20 servos, you might need it. Heck, the fact that you don't have to drill all those dang holes is incentive enough to give it a try.
The traces can get a bit small if you're etching your own boards, especially if you're trying to run them between legs of an SOIC chip, but it's far from impossible with good etching technique.
I'm just saying don't completely count out SMD for your project...SMD components are well within the realm of home-brew electronics. Even for a newbie like me.