Hi Kelly,
I can recommend you to a few of good plugins to manage Ad Ad banners on wordpress site. They are simple but effective to manage which you are needing which you wanting
1. WP125
This is a plugin to manage advertising with 125×125 size on wordpress blogs easily. This plugin also allows the administrator to monitor the number of clicks for each banner ad and can put an ads expiration time which means you intend ads posted automatically removed during the period of the plugin installed. This plugin is perfect for small ads.
Download here
2. BuySellAds
This plugin simply give you 2 options to insert code from buysellads advertising network. You can use the widget or insert content directly to the advertisers want to display in your wordpress site. Of course, your blog needs to approved from BSA network before using this plugin.
Download here
3. Wp-Insert
This is a great plugin and very easy to manage ads on your WordPress blog. With WP-insert you can manage advertising, google analytics, code snippets...etc
Download here
4. OpenX WordPress Widget
OpenX WordPress Widge is a simple plugin for the website to place ads from OpenX websites.
Download here
5. AdRotate
This plugin allows you to place ads and manage banner ads and display multiple ads from the dashboard or website. You can preview the ads that will be shown how before putting it out websites. This plugin even allows track statistics, alerting you on email as one of the banner is about to expire. A perfect plugin in advertising must have on your collections about Ad Management Plugins.
Download here
6. Post Layout
Great plugin for ad insertion in anywhere in your post or even in the first or end of the post.
Download here
7. AdPress
Manage your own website and mobile ads directly from your WordPress admin panel. Using shortcodes or widgets to place graphic banners, buttons or ads on the tower anywhere on your site.
Download here
Summary
Using which plugin depends on your requirements and your hobbies for that plugin. I hope you will choose best Ad Management Plugins for your Wordpress site. Don't forget that when you apply this plugin then your blog needs to have a decent traffic to provide your advertisers quality traffic. Don't make them bored
Hope it helps!