We often want to give all kinds of fun things for singles to do when our focus needs to be more on bible study and prayer. Doing less with more strategy is better. Doing less also helps the leaders not get burned out.
Answer: I believe all singles events/socials need to be strategic fellowships. Meaning, there is careful prayer and planning regarding the purpose of the event, the goals, etc. There needs to be intent of reaching lost singles as well as encouraging saved singles. There needs to be strategy in what you are doing. Leaders need to be used throughout to help reach the goals, connect singles and provide followup feedback.
I have found that if you plan prayer times and/or bible studies, the singles will connect to do other things. I only plan a social (strategic fellowship) once month and plus one Sunday lunch..both as a gateway to bring singles into the church. I encourage singles to plan their own events and promote within their Sunday school classes, bible studies, home groups, etc...keeping in mind if they use the name of the church they have to get prior approval of what they are doing.
I want the singles to take ownership of the "next step" regarding building relationships. I want girls to hang and shop and guys to go watch a football game at the local restaurant. I want older ladies to go on a road trips and young adults to play in the park. By singles coming up with their own stuff and inviting folks they know will come, they take ownership. Big group events aren't always better as you don't build the relationships with them.
Also, plan less stuff but make it more strategic, getting other pastors involved by serving and other leaders involved. Sell tickets or something to get folks to commit. Singles will ALWAYS wait to the last minute to see if something else comes up. Most singles are looking for a mate. If an event always has the same singles at it, they are less likely to come back. Yes, we want them to choose God and then builiding friendships but the reality is most come for the flesh at first. This is why I am big on prayer/study only with the special monthly event or occasional conference/retreat. This way, I am providing what will get singles to God...then allowing God to direct them.
Remember, we build ministry by the one-on-one relationships, by prayer and study...all the rest will just happen. At the last several singles directors jobs I have had, I have made that my focus and somehow, someway the singles find each other and hang. It has ALWAYS worked.
Note: When you are do city-wide ministry there is even a harder time connecting churches and singles. Especially when one church is the main host/location. Other churches will see it as a threat. One way to help this is to move your events to different churches (but again, you might have a denomination issue then) or non-church location. Make sure you leaders of your group reflect the various churches and age/sex u are trying to reach.