My boyfriend and I got out first tandem (Co-motion speedster, large/small) over Christmas. He's 6' and I'm 5'4". We've put about 300 miles on it. My problem is that I can ride 100 miles on my single bike without butt discomfort, but can only do 30ish on the tandem. I have the same saddle on both bikes. The top tube is significantly shorter than my single, and I have the stem pushed in as far as it will go without my face in his butt. This puts me much more upright than on the single. Sliding the saddle back puts my knees too far back, which causes pain above the knees.
We had rented a medium sized Co-motion and I found there to be more room in my space. I don't know why since the top tubes are all the same length, and his saddle is as far forward as it can go.
I've been reading alot about suspension seatposts. I don't notice the bumps being a problem, seems more like more of my weight is on my sit-bones and less spread out over the length of the saddle. I've been trying to stand periodically and pedal standing, but this only helps minimally.
Should I try a suspension post? A softer saddle?