Routine is good.....structure (at least too much of it at this age) is not-so-good. I've got 3 girls (5, 3 and 9 months) and I find that just the getting ready for meals, eating them, cleaning them up - 3 times per day, plus a snack - is enough routine for us!
I think you should let your children play what they want. If they look restless, take 'em for a walk. If they seem a little under the weather, then read to them. With kids this young it's important to take their moods and feelings into consideration.
As far as the kids' activities day to day, I may say that 'today we're going to do a craft after lunch' and then let them loose with scissors, glue, paper and random things to glue. Or play-doh.
But I don't march them into the playroom and say 'ok, it's time to play dolls for 20 minutes then it's on to blocks'. LOL