I did a bit of number crunching and came out with the conclusion that micro management pays off!
Popsicles, net profit= +3120coins/hr, assuming you made it every minute for an hour. but you gain no experience.
mp3 players take two days. net profit= +479.17coins/hr, 5.2exp/hrthis is good if you don't play for hours straight :P
I think the best way to gain is through contracts with the following two items.
candy bars. net profit= +1800coins/hr, +72exp/hr.
mini pretzels. net profit = +2400coins/hr, +40exp/hr
I have four contracts running. two are candy bars and two are mini pretzels.