For the 55, the AquaC Remora (regular) with the MaxiJet upgrade runs around $160. When you add the surface skimming box accessory, that pushes you up to about $200.
I have a Remora Pro with the Mag3 upgrade on a 120g (with surface skimming box), and it seems to keep my tank happy (that, and all the live rock, live sand, etc.)
I have heard that seaclones should be left alone.
For the 100g, get an in-sump skimmer as opposed to a hang-on-tank. I've heard good things about the AquaC Urchin, but have no personal experience.