My charges are 18 month twins and our schedule is pretty repetitive as well but, it works well for us and when I get a little stir crazy we mix things up for a day or two. Our days look like this:

Diaper time (run around in their bedroom)
Breakfast
Inside Play (songs, sensory bins, art- pudding finger paint is perfect for this age!)
Outside (walk, wander, playground, ball)
Story Time
Lunch
Nap
Snack
Outing
MB gets home

One more thing, if they're good enough walkers and the area is safe enough, go out for walks without the stroller. Just let them walk, they usually like walking on their own looking around at stuff.

One thing I learned when it comes to filling up a day, there's no need to rush things that are going good. So if they're doing an art project, as long as they're having fun, let it go on as long as possible. Same with walks or playing in the sand, whatever.

PP here, but when weather kept us inside we'd do lots of art and cooking. Age appropriate obviously.

Like PP said, be thankful for pinterest! Back when I nannied this age child pinterest didn't exist.

When I took care of toddlers I would go to the park daily. It was just part of our regular day unless we had something special planned. I would get super bored at their house, MB worked from home and was always hovering, so we would leave shortly after breakfast and stay gone until nap time (packed a lunch). There were two parks in the area, we'd switch off. Then in the afternoon, after nap, we'd go out again to either a playdate's house, library, or the shopping center near by...or even the park again! Rainy days SUCKED!

You didn't mention art. Do art.

Pinterest activites! A serious life saver when I cared for two toddlers!!!

Also, arts and crafts supplies are great for eating up 30-60 minutes depending on how long they can concentrate! I bought the huge rolls of white paper, crayons, glitter, glue, finger paints, foam adhesive peices etc.

Good luck! It's a hard age!

I am 4 weeks into a new nanny share with two 1 1/2 year olds. Fun age but not yet at the age where a lot of structure is doable. There's a park and library with story time nearby and we frequent both of them several times a week. That does help break up the monotony of the mornings before lunch and nap time. But besides going 45 minutes downtown for the occasional trip to the zoo, museum, or aquarium (MB wants to keep those trips VERY occasional), I feel we are running out of stuff to do. We read books, blow bubbles, sing songs, dance, roam around the play areas of the house and outside, go for stroller walks, etc. But it is starting to feel so repetitive. If anyone has any ideas or resources for new ideas of things to with this age, I'd be very appreciative. Thanks!