A raid fleet of six Infiltrators can be incredibly powerful on the ground. I like to send them in, hotkeyed in groups of two, and have them move as a group. I'll build a bacta tank somewhere if possible, and turn most of the other build pads I encounter into anti-vehicle turrets. If I encounter speeder bikes or stormtrooper squads, I just issue a stop command to the Infiltrators and the enemy troops are cut down in a few volleys of rifle fire. Infiltrators are capable of outrunning detonators dropped by speeder bikes, so they offer no contest. AT-ATs warrant all six Infiltrators tossing their detonators. I find that the toughest opposition comes from the mid-range vehicles: AT-STs and TIE Maulers can squish them, and 2-M tanks carry those nasty anti-infantry blaster cannons. However, smart placement of detonators and spreading out the group of Infiltrators can do some serious damage to those units, especially with the splash damage from detonators attached to vehicles in groups. Now against a human opponent, TIE Maulers are probably enough to take down Infiltrators.
I find that if I can get two or three Infiltrators to plant explosives on an Imperial building, that usually takes it down. It's actually cost-effective to trade three Infiltrators for any one Imperial building, so I figure if I can take out some serious manufacturing infrastructure or expensive high-tech stuff, I've done pretty well. Taking out a single factory or barracks on a world given over to research facilities or mining can also be great prep work for a raid fleet of speeders or artillery.
The cheapest thing I've done with them was raid Geonosis, on which the Imperials had one of every unit-producing building and a magnapulse cannon, but no units other than the building garrisons. I immediately took every Geonosian on the planet and issued a suicide attack order on the Imperial base, distracting them enough so that the Infiltrators could move with impunity. With the Infiltrators, I destroyed the Imperial heavy factory...and then I retreated. I raided again immediately, only this time, I didn't have the garrison of 2-M's to account for. Took out the advanced factory and retreated--et cetera, et cetera. The game really ought to have a time limit on how often a given planet can be raided, just to prevent things like that.