J.L.
Go to the library! I take my kids (DD 3 yr, DS 19 months) to different libraries all throughout the week and rarely for the story times, it's just to hang out and get out of the house without spending money. Most of the libraries in my area are very nice with play areas for the kids. Its great because you can put your 10 month old down and let your 3 yr old look at some picture books.