Our house has baseboard heaters on almost all the walls in each room. It's annoying as heck. With our sectional (fabric), we placed it a couple of inches or so away from the baseboard heaters. We also placed our bed the same distance. Any other pieces of furniture will basically have to be placed this way.
Edited: Hmm... I'm really bad at determining distance, so maybe my "couple of inches" is wrong after reading the other responses. I'm not in that house now, so I can't measure exactly what it is, but I think it might be closer to 8"-10" from the baseboard heaters. We're going to the house tonight so I'll make another edit when I can measure the actual distance then.
Edited again: Yup, everything is about 8"-10" from the baseboard heaters. Ours are hot water, so they don't get terribly hot.