I also have a requirement to send sms messages to large groups of people so being a recent user of Droid (Samsung Galaxy S2) I found it very frustrating to find an app that managed this most basic of functions on a Blackberry.
After some trial and error on a few apps i.e. Handcent, Go SMS Pro then Chomp SMS
https://market.android.com/details?id=com.p1.chompsms&hl=en I decided on Chomp and have actually paid for the app and it works great.
Handcent was very good but I found it tiresome because when sending a group message it listed each recipient individually in the menu which meant if someone responded and I needed to reply to all I had to go back into my contacts to select the group again.
Go SMS Pro looked to have overcome this problem as it listed just one entry in the message list with the message. However, I had problems trying to get Go SMS Pro to read the groups I had already setup within my contacts ( I use Gmail and sync my contacts from there.)
Finally I tried Chomp SMS - it lists the sent message under one entry in the inbox and reads the Groups in my Contacts effortlessly.
It is a free APP but whenever it did waht I needed I purchased it to remove the small ad. So fo