You might like to try G Em C D7 and back to G. Or D C G and back to D. I suppose the commonest progression is just C F G7 C. Ragtimey sort of progressions are C E F D7 G7 or C A7 D7 G7 C.

As I think you can grasp from the stuff already written (very clear and helpful I think) you can play these progressions (or relationships as I like to think of them) in any key. So the first would become C Am F G7 in C or D, Bm,G A7 in D.

The great thing about these sort of 'standard progressions' is the bits writers throw in to vary them.