Saylorville is an extremely busy lake on holiday weekends, and throughout most of the summer. Its close proximity to Des Moines means that this lake sees a lot of boat traffic.
Boating North of Mile Long Bridge is not advised as it becomes very shallow when the lake is at normal pool levels.
My family and I find this lake to be too busy, too rough, and generally the facilities (bathrooms, beaches, etc) are not at the same level as Lake Red Rock or Lake Rathbun, (the other Army Corps of Engineers managed reservoir's).
We haven't been on it in 2-3 years, preferring to drive to lakes away from Des Moines for a little more elbow room.