I live in west Olathe and I have to HIGHLY recommend the folks at Kids Day Out (located at Westside Nazarene, just west of Parker on Santa Fe). They offer two programs - a "mom's day out" and a pre-school. My daughter started there when she was two (she's in 1st grade now) and my 2.5 yr old son attends now the "day out" program now.
Their preschool program truly prepared Lizzie for kindergarten and the classroom setting. The classes are 1/2 day, Tues-Thurs. You can choose between am or pm. They also offer Wednesdays as a full day for small monthly fee. Many preschoolers with younger siblings attend this session while their sibs are in Kids Day Out. It's a great way for mom to get some time out to herself.
Call Cindy (director) and Sue (asst director) ###-###-#### Tues thru Thurs from 9am to 3 pm. They're enrolling now for next fall. Just tell them that F. sent you! :D