E.P.
Whatever you do... make your reward system SIMPLE or your children will be bickering about the system! Come up with a reasonable allowance payout, per week. Personally, I would just give each child a chore list, some items ALL children are expected to do (morning stuff like make bed, pick up dirty clothes, keep bathroom organized, and some evening stuff, etc...). Then, give each child a specific chore or two that is expected of them each day (i.e. one cleans off table, one sets table, one dumps garbage,...) This will ALWAYS be their chore - again, keep it simple. Let them agree to the job they will do - any switching off can be arranged between the children - but it's their responsibility to do that. Some "extra" jobs are just negotiated on the spot, but I don't believe in paying a child for every extra job - everyone is expected to do their part to maintain the home. Giving them money helps them learn how to save and work toward a goal. It's not a free handout. they can get docked too, if their jobs aren't done satisfactorily. I loved getting an allowance as a kid - we're passing on the tradition!
I personally think that marble jars may work in school but... as a parent, it's not something that I would want to monitor all the time. Some of the "behavioral moments are just subjective and arguments will ensue... "(...."When Susie did that.... SHE didn't get a marble pulled--WHY DID I? That's not fair!!") ON a weekly basis, when all has gone well, just going out for ice cream, playing a board game or taking a trip to the park can be a good award and time spent with the family, together.
Also, we have a "no fire drill in the morning rule" in our home. That means that things are done on a timely basis. You do your morning routine and you it to the best of your ability, and do it peacefully (i.e. no yelling, no fuss, make your bed, pick up old clothes, brush teeth, comb hair, eat breakfast, feed the dog). Also, the night before (and I used to make my kids write their reminders on post-it notes) .. .lay out clothes for next day, take a shower, organize stuff for backpack. Of course, homework is a given.
If they cause a "fire drill" in the morning (i.e. totally disorganized and running around like a chicken without a head!) they get ONE GRACE PERIOD. After that, if it happens, I implement the "no fire drill rule" and they are instantly grounded for one hour, AFTER SCHOOL, AFTER all homework is completed, (which they hate because they usually do homework after dinner!) , AFTER dog is walked and ALL forgotten chores are done - their hour begins! The "hour" grounding doesn't sound like a big deal but with all the stuff that they have to do after school - they are flying around to just get to their hour grounding. When they have a friend or two ringing the doorbell just after school on a beautiful day... it's rough! Mornings are good here!
Good luck.