Manage the Time
One way to help keep the sharing time from dominating and preventing the group from actually praying is to focus on one person at a time. Have that person share a prayer request, and ask the questions that need to be clarified in order to go to prayer. Then have the group pray over that request until there is a sense that the situation has been covered sufficiently in prayer. Have someone close out that prayer time and then move on to the next person.
I favor this method over having everyone share first and then having everyone pray for several reasons. First, focusing on one person at a time helps group members remember what to pray for. It can be difficult to remember, after 6 people have talked for 20 to 30 minutes, what the first one wanted prayer for. Second, such a focus promotes agreement in prayer as the group focuses together on one person, rather than skipping around from person to person. This focus will also result in covering each person in the group more thoroughly in prayer. Finally, breaking up the time between sharing and prayer helps keep people involved and concentrating as compared to long periods of sharing and then long periods of prayer (which can lend themselves to people tuning out over time).
If some group members have difficulty expressing their prayer requests succinctly, you may want to consider having everyone write down their requests on an index card (either before coming or during group time). This may help members organize their thoughts. Further, you may want to have group members switch cards before going to prayer, and have each person read the requests on the card they received and then lead the group in prayer for the person who wrote the card.