After you finished a contract, maybe you can get a message from the contractor like "that was great work, etc etc, talk about stuff, etc etc, more contracts, etc etc" i think it would be really nice.
Edit: You could even add messages when certain conditions are met! For example: if you arrived in moobln's SOI, then you could have pricklespac send a dialogue like "I see that you've arrived within the moon's gravity well, I hope you can land safely, I would like the data as soon as possible" etc