There are strengths and weaknesses with all options available to use for advertising your product or services.
Radio is intrusive and local, it offers mobility and low production costs. You can target your message by station format and/or time-of-day or day-of-week. One weakness of radio is that it offers no visual but with the right copy, the listener can create their own "theatre of the mind" image. Radio is looked upon as a frequency medium, however, it can be quite expensive to build reach without purchasing a number of stations.
Maximize radio dollars by looking at all dayparts and obtaining guarantees on rotation throughout days of the week and hours within each daypart. Look at stations other than the leader and leverage one station's delivery against others you are considering.
Don't forget about added value. It can come in many forms including no charge spots, billboards, and sponsorships or streaming exposure to catch those who listen on their computers while at work.