If you're looking for some combinations of chords which sound "right" following each other, have a search for info on cadences. IMO a lot of piano riffs, in fact a lot of chord progressions in house music, follow a relatively small set of basic chord patterns.
A cadence is pretty much a way of 'resolving' a piece of music in a way which will make sense and sound good. When a piece of music or a set of chords is 'resolved' in effect this just means it will make musical sense when it's looped. There are only a few basic types of cadence to get your head around.
The trick is to listen to the bassline of a track. Work that out on a keyboard, then add the basic triads etc. to each bass note in turn. When you get to that point, you can change the tone & feel by filling some or all of the chords out a bit more, by doing things like adding the 7th or dropping the middle note from the triad... adding another note a full octave lower or higher than the top/bottom note etc. to change the emphasis... then you can start to get cleverer and intersperse the basic progression you've figured out with further chords to transition from one point in your progression to the next.
Get to grips with that lot and I reckon you'll be off and running coming up with your own piano licks.
