I don't have a lot of people on my friends list so I just jump into matchmaking. I find myself playing the level with the bomb and the northern pylon level over and over again. I'm level 9 and played the volcano for the first time today. I don't think I've done much in pacific to be honest. It's kinda strange.

Maybe they match you up by level. Before I hit level 10 I played on the bomb level a lot (sinkhole?) and a couple of other levels. After hitting level 10 I only seem to get matched with people who want to play on Volcano, which is probably the most difficult to get gold on. They all have high level gear and when I check achievements they generally don't have the one for gold on every mission, so they keep trying that one over and over. After watching them play I can understand why they haven't gotten it yet. It gets a bit frustrating. Today I got lucky and found three good people and we just played through Africa together.

Oh man do I feel you on that...it was frustrating at first, as I was early in the story and groups were just hitting boss levels and such. Now that I'm level 10 and have some decent weapons, I find people tend to go more for Volcano, Vlad and other than that it can be a bit random. I guess sometimes guys just want to gold a particular level. I've not found a group yet that is content to just go through them mission by mission.

I've only played single, so I keep grinding out the same levels to get Gold...